There are several requests to be able to assign several milestones to the case. Specifically, we support several versions with separate (branched) code bases. Bugs and features may need to be resolved and independently verified for several milestones.
I understand that having multiple milestones for a single case, and options to have this case in different states (open, resolved, closed) for different milestones will make UI confusing. Having the case duplicated would work, but it is a hastle to create duplicated cases manually. I suggest that FogBugz automates case duplication. So the use case would be: - enter the case and assign a milestone - assign additional milestone to the case, which duplicates this case and makes it a subcase of the first.