If the requirements are setup in TD as:
Business Requirement - parent
Functional Requirement - child

- FR1
- FR2

- FR1

and you have a child requirement that applies to multiple parent requirement - I would assume if I mapped my test case to the Functional Requirement (child) that TD would make the same mapping across the board to the other Business requirements (parent) that applied.

From what I see, I will have to do this manually. Is there anyway around this?