[Urgent] - Driving Sub Assembly Dimension

I have an assembly that is totally parametric. I want toderive a distance mate from one of the sub-Assemblies through thedesign table of the top level assembly.
I don't know how to do it. because when I pick the mate Dimension Idoesn't go to the Design Table.
Does any one know any way around thatSolidworksConfigurations design Tables