Allocated resource replacement

Hi,
This is not an issue.
A new assignment to the new resource is created to replace old one, even if new resource is already assigned to the activity.
This helps you differ previous from new one.
And planning calculation is designed to allow multiple assignments of same resource to same activity.
There are different use cases for this :
- add extra work for instance an amendment to the original order), when you want to distinguish original and amendment
- allocation with different "functions" that give different cost, such as "with travel epense / without travel expense" or "normal fee / extra xork fee"
- replacement with resource already allocated to the acitvities