Global Variable Linking?

I am trying to create a fully parameterized top level assembly with multiple sub-assemblies. I do not want to create a whole bunch of configurations, but rather one configuration that can be saved to a different (job specific) file name and then modified to meet design requirements. I have been using Global variables in the top level assembly to input my design parameters and update the model accordingly. I have found that the global variables can be used to drive features (and thus part specific design tables) on the next highest level. If I want the part to update properly after I change a global variable then I have to open the sub assembly that changed, open its design table and then let it refresh. I dont think this is the best way to do this, and I believe there is probably a cleaner way to parameterize assemblies. Also, I still cannot use the top level global variables to drive sub-sub-assembly parts because it won't link.

Is there any way to drive global variables in sub-assemblies with global variables in the top level? This would eliminate a bunch of configurations and a tedious process to update the whole assembly.