Before I edit an xml or ditamap how can I tell where else they are used?

When I started working with FrameMaker 10 (Structured) I knew this might become a problem someday. I started with a set of existing manuals that draw on existing reservoirs of ditamaps and xml files. When I have to edit an xml file how can I know where else it is used? Because if the change I am making in one manual is not intended to show up in a certain other manual I will have to change the name of the xml file and possibly the ditamap it is used in.

any help appreciated,

Mike