Converting a branch into category does not convert all descendants

Old versions

This question refers to older SuperMemos. Categories were replaced with concepts.

Question

Converting a branch into a category does not convert all the descendants into descendants of that category. If I check the descendants using Ctrl+Alt+P, they all still belong to the old category. Is there a fast way to convert all descendants into descendants of that category while (1) maintaining the branch structure and (2) applying the category template to all items in the branch?

Hint

Probably the only way to move items to a category is Move to category (in Contents). This does not preserve the tree structure. This sounds like a useful idea for future versions, esp. that you are not the first to ask.