diff --git a/booking.studygroups.inc b/booking.studygroups.inc
index 23171ba..3a17570 100644
--- a/booking.studygroups.inc
+++ b/booking.studygroups.inc
@@ -221,24 +221,32 @@ function booking_studygroups_calculate() {
 	global $event;
 	$attendees = array();
 	$working_list = array();
+	
+	//delete from booking_studygroup_mapping;
+	//alter table booking_studygroup_mapping AUTO_INCREMENT=1;
 
 	//consider using a lock as per https://api.drupal.org/api/drupal/includes!lock.inc/group/lock/7
 
 	//select all the study groups for this event id
-	$studygroups = db_query("SELECT * FROM {booking_studygroup_list} WHERE booking_eventid = :eid", array(':eid' => $event->eid));
+	$studygroups_query = db_query("SELECT * FROM {booking_studygroup_list} WHERE booking_eventid = :eid", array(':eid' => $event->eid));
+	$studygroups = $studygroups_query->fetchAllAssoc('sid');
 	
 	//calculate the max number of attendees in a group
-	$firstgroup = $studygroups[0];
+	$firstgroup = reset($studygroups);
 	$limit = variable_get('booking_regn_limit','500');
-	$max_people = (int) ($limit / $firstgroup->booking_num_group_sessions);
+	//add an extra one to the maximum size, to cater for some larger groups when the number of people doesn't divide evenly
+	$max_people = (int) ($limit / $firstgroup->booking_num_group_sessions) + 1;
 	
-	drupal_set_message(t('Fitting !num people in each group.', array('!num' => $max_people)));
+	//drupal_set_message(t('Fitting !num people in each group.', array('!num' => $max_people)));
 	
 	//select all the attendees booked in
-	$query = db_query("SELECT * FROM {booking_person} p left outer join {booking_leadhelp_list} l on p.nid = l.booking_node_id WHERE p.booking_event_id = :eid AND p.booking_status = 1", 
+	$query = db_query("SELECT p.nid, p.booking_partner_id, p.booking_event_id, p.booking_status, l.booking_total_lead, l.booking_available_lead, l.booking_total_help, l.booking_available_help FROM {booking_person} p left outer join {booking_leadhelp_list} l on p.nid = l.booking_node_id WHERE p.booking_event_id = :eid AND p.booking_status = 1", 
 					array(':eid' => $event->eid));
 	$attendees = $query->fetchAllAssoc('nid');
 	
+	//create an array to keep track of the number of people in each session for this group
+	$session_count = array();
+	
 	//select any entries already in the mapping table
 	$group_mapping = db_query("SELECT * FROM {booking_studygroup_mapping} WHERE booking_eventid = :eid", array(':eid' => $event->eid));
 	
@@ -263,7 +271,8 @@ function booking_studygroups_calculate() {
 	//iterate over each study group (eg Monday Tuesday Wednesday etc)
 	foreach ($studygroups as $group)
 	{
-		drupal_set_message(t('Processing study group !group.', array('!group' => $group->booking_studygroup_descrip)));
+		drupal_set_message(t('Processing study group !group with !sessions sessions.', 
+			array('!group' => $group->booking_studygroup_descrip, '!sessions' => $group->booking_num_group_sessions)));
 		
 		//create a temporary copy of the attendee list to work with for this study group
 		$working_list = array();
@@ -272,6 +281,10 @@ function booking_studygroups_calculate() {
 		$obj = new ArrayObject( $working_list );
 		$it = $obj->getIterator();		
 		
+		//clear the array keeping track of the number of people in each session for this group
+		for ($i = 1; $i <= $group->booking_num_group_sessions; $i++)
+			$session_count[$i] = 0;
+		
 		//reset the iterator to starting position
 		$it->rewind();
 		
@@ -290,7 +303,9 @@ function booking_studygroups_calculate() {
 			{
 				if ($rewound == TRUE)
 				{
-					watchdog('booking', "Already rewound once.");
+					//watchdog('booking', "Already rewound once.");
+					drupal_set_message(t("Error: Reached end of attendee list before allocating all study group leaders/helpers for group !group.", 
+										array('!group' => $group->booking_studygroup_descrip)), 'error', FALSE);
 					//we've already gone back to the start once, don't do it again
 					break;
 				}
@@ -315,15 +330,16 @@ function booking_studygroups_calculate() {
 				$helper_found = FALSE;				
 			}
 
-
 			//get the current attendee element
 			$current = $it->current();	
+			$key = $it->key();			
 			//watchdog('booking', 'Attendee before leader check has id !id.', array('!id' => $it->key()));
 			
-			//check if this attendee is a leader
-			if ($current->processed == 0 && $current->booking_available_lead > 0 && $leader_found == FALSE)
+			//check if this attendee can be a leader
+			if ($leader_found == FALSE && $current->processed == 0 && $current->booking_available_lead > 0)
 			{
-				drupal_set_message(t('Found available leader with id !id for session !session.', array('!id' => $it->key(), '!session' => $session_id)));
+				drupal_set_message(t('Found available leader with id !id for session !session (currently with !num people).', 
+						array('!id' => $it->key(), '!session' => $session_id, '!num' => $session_count[$session_id])));
 				
 				$leader_found = TRUE;
 				
@@ -331,48 +347,68 @@ function booking_studygroups_calculate() {
 				$current->session = $session_id;
 				$current->processed = 1;
 				$current->is_leader = 1;
+
+				//keep track of the number of people in this study group session
+				//$session_count[$session_id] = $session_count[$session_id] + 1;
 									
 				//decrement the number of available leading positions for this user in our master copy of the attendee list
-				$attendees[$it->key()]->booking_available_lead = $attendees[$it->key()]->booking_available_lead - 1;
+				$attendees[$key]->booking_available_lead = $attendees[$key]->booking_available_lead - 1;
+				
+				$partner_id = $current->booking_partner_id;
 				
 				//Check for spouse of leader, allocate to this group also
-				if ($current->booking_partner_id > 0)					
+				if ($partner_id > 0)					
 				{
 					//add the spouse to the same session and mark as processed in the temporary attendee list
-					drupal_set_message(t('Assigning spouse (id !spouse) of id !id to session !session.', 
-						array('!id' => $it->key(), '!session' => $session_id, '!spouse' => $current->booking_partner_id)));							
+					drupal_set_message(t('Assigning spouse (id !spouse) of id !id to session !session (currently with !num people).', 
+						array('!id' => $it->key(), '!session' => $session_id, '!spouse' => $partner_id, '!num' => $session_count[$session_id])));							
 					
-					$spouse = $working_list[$current->booking_partner_id];
-					$spouse->session = $session_id;
-					$spouse->processed = 1;	
+					//$spouse = ;
+					$working_list[$partner_id]->session = $session_id;
+					$working_list[$partner_id]->processed = 1;	
+					//add two people to this session
+					$session_count[$session_id] = $session_count[$session_id] + 2;
 				}
+				else
+				{
+					//only add one person to this session
+					$session_count[$session_id] = $session_count[$session_id] + 1;
+				}				
 			}
-			//check if this attendee is a helper
-			elseif ($current->processed == 0 && $current->booking_available_help > 0 && $helper_found == FALSE)			
+			//check if this attendee can be a helper
+			elseif ($helper_found == FALSE && $current->processed == 0 && $current->booking_available_help > 0)			
 			{
-				drupal_set_message(t('Found available helper with id !id for session !session.', array('!id' => $it->key(), '!session' => $session_id)));
+				drupal_set_message(t('Found available helper with id !id for session !session (currently with !num people).', 
+									array('!id' => $it->key(), '!session' => $session_id, '!num' => $session_count[$session_id])));
 				
 				$helper_found = TRUE;
 				
 				//assign leader to session and mark as processed in the temporary attendee list					
 				$current->session = $session_id;
 				$current->processed = 1;
-				$current->is_helper = 1;				
+				$current->is_helper = 1;
+				//$session_count[$session_id] = $session_count[$session_id] + 1;			
 				
 				//decrement the number of available helping positions for this user in our master copy of the attendee list
-				$attendees[$it->key()]->booking_available_help = $attendees[$it->key()]->booking_available_help - 1;	
+				$attendees[$key]->booking_available_help = $attendees[$key]->booking_available_help - 1;	
+				
+				$partner_id = $current->booking_partner_id;
 				
 				//Check for spouse of helper, allocate to this group also
-				if ($current->booking_partner_id > 0)					
+				if ($partner_id > 0)					
 				{
 					//add the spouse to the same session and mark as processed in the temporary attendee list
 					drupal_set_message(t('Assigning spouse (id !spouse) of id !id to session !session.', 
-						array('!id' => $it->key(), '!session' => $session_id, '!spouse' => $current->booking_partner_id)));							
+						array('!id' => $it->key(), '!session' => $session_id, '!spouse' => $current->booking_partner_id)));			
 					
-					$spouse = $working_list[$current->booking_partner_id];
-					$spouse->session = $session_id;
-					$spouse->processed = 1;	
-				}							
+					$session_count[$session_id] = $session_count[$session_id] + 2;								
+					$working_list[$partner_id]->session = $session_id;
+					$working_list[$partner_id]->processed = 1;		
+				}
+				else
+				{
+					$session_count[$session_id] = $session_count[$session_id] + 1;
+				}						
 			}
 			//otherwise go to the next one
 			else
@@ -380,9 +416,14 @@ function booking_studygroups_calculate() {
 				$it->next();
 			}
 		}
+		
+		//watchdog('booking', "Attendee list: @info", array('@info' => var_export($session_count, TRUE)));
 
 		//reset the iterator to starting position
 		$it->rewind();
+		
+		//set our counter
+		$i = 1;
 	
 		//iterate over the attendee list
 		while ( $it->valid() )
@@ -398,57 +439,103 @@ function booking_studygroups_calculate() {
 					drupal_set_message("Ran out of attendees to process.");
 					break;
 				}										
-			}			
+			}		
+			
+			if ($i > $group->booking_num_group_sessions)
+				$i = 1;				
+			
+			//TODO
+			//Change this from a for loop
+			//to a check to see if a counter is greater than the number of sessions
+			//if it is then set it back to 1
 			
 			//iterate over the session list
-			for ($i = 1; $i <= $group->booking_num_group_sessions; $i++)
+			//for ($i = 1; $i <= $group->booking_num_group_sessions; $i++)
 			//for ($i = 1; $i <= 16; $i++)
-			{	
-				//check we have attendees left
-				if (! $it->valid() )
+			//{	
+			//check we have attendees left
+			if (! $it->valid() )
+			{
+				drupal_set_message("Ran out of attendees to process.");
+				break;
+			}
+
+			//check this session has room in it			
+			$break_condition = false;
+			while ($session_count[$i] > $max_people)
+			{
+				drupal_set_message(t("Session ID !id is full, moving to next session for user id !nid", array('!id' => $i, '!nid' => $it->key())));
+				$i++;
+				//reset the counter if we go past the end
+				if ($i > $group->booking_num_group_sessions)
 				{
-					drupal_set_message("Ran out of attendees to process.");
-					break;
-				}
-					
-				//get the current attendee element
-				$current = $it->current();					
-				
-				//assign this attendee to this session if unprocessed so far
-				if ($current->processed == 0)
-				{				
-					drupal_set_message(t('Assigning person with id !id to session !session.', array('!id' => $it->key(), '!session' => $i)));
-					$current->session = $i;
-					$current->processed = 1;
-					
-					//check if the attendee was married
-					if ($current->booking_partner_id > 0)					
+					$i = 1;	
+					//make sure we don't get stuck in an infinite loop - only go past the end once
+					if ($break_condition == true)
 					{
-						//add the spouse to the same session and mark as processed in the temporary attendee list
-						drupal_set_message(t('Assigning spouse (id !spouse) of id !id to session !session.', 
-							array('!id' => $it->key(), '!session' => $i, '!spouse' => $current->booking_partner_id)));							
-						
-						$spouse = $working_list[$current->booking_partner_id];
-						$spouse->session = $i;
-						$spouse->processed = 1;	
+						drupal_set_message("Ran out of sessions that aren't full to place attendees into.");
+						break;
 					}
-				
-				}	
+					$break_condition = true;
+				}			
+			}
 
-				//move to the next unprocessed attendee in the list
-				while ($it->valid() && $it->current()->processed == 1)
-					$it->next();
+			/*
+			if ($session_count[$i] > $max_people)
+			{
+				drupal_set_message(t("Session ID !id is full, moving to next session for user id !nid", array('!id' => $i, '!nid' => $it->key())));
+				//$i++;
+				continue;
+			}
+			*/
+			
+			
+			//get the current attendee element
+			$current = $it->current();					
+			
+			//assign this attendee to this session if unprocessed so far
+			if ($current->processed == 0)
+			{				
+				drupal_set_message(t('Assigning person with id !id to session !session (now with !num people).', array('!id' => $it->key(), '!session' => $i, '!num' => $session_count[$i])));
+				$current->session = $i;
+				$current->processed = 1;
+				$partner_id = $current->booking_partner_id;
 
-			}	//finished looping through session list
+				//check if the attendee was married
+				if ($partner_id > 0)				
+				{
+					//add the spouse to the same session and mark as processed in the temporary attendee list
+					drupal_set_message(t('Assigning spouse (id !spouse) of id !id to session !session.', 
+						array('!id' => $it->key(), '!session' => $i, '!spouse' => $current->booking_partner_id)));							
+					
+					$working_list[$partner_id]->session = $i;
+					$working_list[$partner_id]->processed = 1;	
+					$session_count[$i] = $session_count[$i] + 2;
+				}
+				else
+				{
+					$session_count[$i] = $session_count[$i] + 1;
+				}
+			
+			}	
+
+			//move to the next unprocessed attendee in the list
+			while ($it->valid() && $it->current()->processed == 1)
+			{
+				//drupal_set_message(t("Skipping attendee ID !id, already processed.", array('!id' => $it->key())));
+				$it->next();
+			}
+			
+			//move to the next session
+			$i++;
+
+			//}	//finished looping through session list
 				
 		}	//finished looping through attendees for this study group	
 
-
+		
 		//iterate over the attendee list and write to the database the session they're assigned to
 		//use the multi-insert query type at https://drupal.org/node/310079
-		
-
-		
 		$insert_query = db_insert('booking_studygroup_mapping')->fields(array('booking_eventid', 'booking_node_id', 
 							'booking_studygroup_id', 'booking_session_id', 'booking_is_leader', 'booking_is_helper'));
 
@@ -466,12 +553,20 @@ function booking_studygroups_calculate() {
 				'booking_is_leader' => $person->is_leader,
 				'booking_is_helper' => $person->is_helper,
 			);
-			$query->values($record);
+			$insert_query->values($record);
 			
 		}			
-		$query->execute();		
+		$insert_query->execute();		
 		
 		
+		//watchdog('booking', "Attendee list: @info", array('@info' => var_export($session_count, TRUE)));
+		
+		//clear the arrays we've been using for this iteration
+		unset($session_count);
+		unset($working_list);
+		
+		//
+		
 	}	//finished processing study groups	
 	
 	//watchdog('booking', "Attendee list final version: @info", array('@info' => var_export($attendees, TRUE)));
@@ -499,34 +594,26 @@ function booking_studygroups_view_form($node, &$form_state, $group_id) {
 	  drupal_get_path('module', 'booking') . '/booking.css',
 	);
 	
-	if ($single_view == true)
-	{
-		//verify that $group_id is a number
-		if (! preg_match('/^[0-9]+$/', $group_id)) {
-			drupal_set_message("Error: Invalid study group ID supplied. Unable to view group membership.", 'error', FALSE);
-			drupal_goto('admin/config/booking');
-			return "";
-		}
-		
-		//collect information on the study group
-		$group = db_query("SELECT * FROM {booking_studygroup_list} WHERE booking_eventid = :eid and sid = :sid",
-							array(':eid' => $event->eid, ':sid' => $group_id))
-				->fetchObject();	
-				
-		if (! $group)
-		{
-			drupal_set_message("Error: Could not find matching study group ID. Unable to view group membership.", 'error', FALSE);
-			drupal_goto('admin/config/booking');
-			return "";			
-		}
-						
-	}
-	else
-	{
-		drupal_set_message("Page not yet implemented.", 'error', FALSE);
+	//verify that $group_id is a number
+	if (! preg_match('/^[0-9]+$/', $group_id)) {
+		drupal_set_message("Error: Invalid study group ID supplied. Unable to view group membership.", 'error', FALSE);
 		drupal_goto('admin/config/booking');
-		return "";		
-	}	
+		return "";
+	}
+	
+	//collect information on the study group
+	$group = db_query("SELECT * FROM {booking_studygroup_list} WHERE booking_eventid = :eid and sid = :sid",
+						array(':eid' => $event->eid, ':sid' => $group_id))
+			->fetchObject();	
+			
+	if (! $group)
+	{
+		drupal_set_message("Error: Could not find matching study group ID. Unable to view group membership.", 'error', FALSE);
+		drupal_goto('admin/config/booking');
+		return "";			
+	}
+	
+	watchdog('booking', 'Study groups id: @info', array ('@info' => var_export($group_id, TRUE)));
 
 	$header = array(
 		'booking_session_id' => array('data' => t('Study Group Session'), 'field' => 'm.booking_session_id', 'sort' => 'asc'),