Example:

• see the attached process diagram
• we want to migrate from the second process definition to the first
• A maps to A, B maps to B, sub process maps to sub process.
• A and B are active when migrating

Current behavior:

• this is currently forbidden (throwing a validation error) because after migration, the instance of A would be no longer a descendant of sub process

Expected behavior:

• this is possible; the instance of A is moved one level up in the activity instance tree
• a validation error should only be thrown if the sub process instance is going to have no more children after migration