Index: lams_common/conf/hibernate/mappings/org/lamsfoundation/lams/learningdesign/Activity.hbm.xml
===================================================================
diff -u -r250486f86b66ac04cece0001879c3dc39c96ed98 -r1274faa8cf4613e5d8537ff2954796f1aa1ed5b5
--- lams_common/conf/hibernate/mappings/org/lamsfoundation/lams/learningdesign/Activity.hbm.xml	(.../Activity.hbm.xml)	(revision 250486f86b66ac04cece0001879c3dc39c96ed98)
+++ lams_common/conf/hibernate/mappings/org/lamsfoundation/lams/learningdesign/Activity.hbm.xml	(.../Activity.hbm.xml)	(revision 1274faa8cf4613e5d8537ff2954796f1aa1ed5b5)
@@ -223,9 +223,10 @@
 		<meta attribute="class-description" inherit="false">@hibernate.class </meta>			
 	    <meta attribute="scope-class" inherit="false">public abstract</meta>
 	    
-	    <!-- bi-directional one-to-many association to Activity-->
-	    <set name="activities" lazy="false" inverse="true" cascade="all-delete-orphan" sort="org.lamsfoundation.lams.learningdesign.ActivityOrderComparator" >
-    		<meta attribute="field-description">@hibernate.set lazy="false" inverse="true" cascade="all-delete-orphan" sort="org.lamsfoundation.lams.learningdesign.ActivityOrderComparator"
+	    <!-- bi-directional one-to-many association to Activity. Don't use all-delete-orphan as the child activity may be removed -->
+	    <!-- from this relationship but not from the database (e.g. moving from an optional activity to the main level in the design -->
+	    <set name="activities" lazy="false" inverse="true" cascade="save-update" sort="org.lamsfoundation.lams.learningdesign.ActivityOrderComparator" >
+    		<meta attribute="field-description">@hibernate.set lazy="false" inverse="true" cascade="save-update" sort="org.lamsfoundation.lams.learningdesign.ActivityOrderComparator"
     										@hibernate.collection-key column="parent_activity_id" 
     										@hibernate.collection-one-to-many class="org.lamsfoundation.lams.learningdesign.Activity"
 			</meta>    										
Index: lams_common/src/java/org/lamsfoundation/lams/learningdesign/ComplexActivity.java
===================================================================
diff -u -rc21079bc26cf334c99c5194da3ae223f7bfec9bb -r1274faa8cf4613e5d8537ff2954796f1aa1ed5b5
--- lams_common/src/java/org/lamsfoundation/lams/learningdesign/ComplexActivity.java	(.../ComplexActivity.java)	(revision c21079bc26cf334c99c5194da3ae223f7bfec9bb)
+++ lams_common/src/java/org/lamsfoundation/lams/learningdesign/ComplexActivity.java	(.../ComplexActivity.java)	(revision 1274faa8cf4613e5d8537ff2954796f1aa1ed5b5)
@@ -104,7 +104,7 @@
 	}
 
 	/**
-	 * @hibernate.set lazy="true" inverse="true" cascade="all-delete-orphan" sort="org.lamsfoundation.lams.learningdesign.ActivityOrderComparator"
+	 * @hibernate.set lazy="true" inverse="true" cascade="save-update" sort="org.lamsfoundation.lams.learningdesign.ActivityOrderComparator"
 	 * @hibernate.collection-key column="parent_activity_id"
 	 * @hibernate.collection-one-to-many class="org.lamsfoundation.lams.learningdesign.Activity"
 	 *  
Index: lams_common/src/java/org/lamsfoundation/lams/learningdesign/service/LearningDesignService.java
===================================================================
diff -u -r2b636f4e834cd0b45c00bb3abf6a6b5e5f3161c8 -r1274faa8cf4613e5d8537ff2954796f1aa1ed5b5
--- lams_common/src/java/org/lamsfoundation/lams/learningdesign/service/LearningDesignService.java	(.../LearningDesignService.java)	(revision 2b636f4e834cd0b45c00bb3abf6a6b5e5f3161c8)
+++ lams_common/src/java/org/lamsfoundation/lams/learningdesign/service/LearningDesignService.java	(.../LearningDesignService.java)	(revision 1274faa8cf4613e5d8537ff2954796f1aa1ed5b5)
@@ -333,22 +333,25 @@
 			OptionsActivity optionsActivity = (OptionsActivity)parentActivity;
 			Set childActivities = optionsActivity.getActivities(); //childActivities should be sorted according to order id (using the activityOrderComparator)
 			Iterator i = childActivities.iterator();
-			while (i.hasNext())
+			while (i.hasNext() && validOrderId)
 			{
 				Activity childActivity = (Activity)i.next();
 				thisActivityOrderId= childActivity.getOrderId();
 				if (previousActivityOrderId != null)
 				{
 					//compare the two numbers
-					if (thisActivityOrderId.longValue() != (previousActivityOrderId.longValue() + 1))
-						validOrderId = validOrderId && false;
+					if (thisActivityOrderId==null ) {
+						validOrderId = false;
+					} else if ( thisActivityOrderId.longValue() != (previousActivityOrderId.longValue() + 1)) {
+						validOrderId = false;
+					}
 					
 				}
 				else
 				{
 					//this is the first activity, since the previousActivityId is null
-					if(thisActivityOrderId.longValue()!= 1)
-						validOrderId = validOrderId && false;
+					if(thisActivityOrderId==null || thisActivityOrderId.longValue()!= 1)
+						validOrderId = false;
 				}
 				previousActivityOrderId = thisActivityOrderId; 
 			}