I need to figure out how to create liquid parts to be added to an assembly, but I have some hurdles – namely the need to have one configuration for that liquid part, and remain linked to the assembly.  I'm not sure if this is possible, but if anyone has a way, it would be a big help.  The main constraint is that I'm in a documentation system that uses EPDM, where files and revisions are strictly controlled.

Let's say that you have some epoxy that needs to go into different assemblies and fill/pot volumes therein.  There are three ways I can think of to get it done, but they all have problems...

1. You might take a part file that is some blunt mass of the stuff, e.g. a simple, transparent, colored cylinder that's of adequate starting size, drag it into the assembly and over the area where it'll reside, extrude/cut the excess on the outside, and then use the cavity command to make it all the right shape and size internally; that would work, but then you are putting that shape change into the part file, which kind of spoils it for use in other assemblies. 
2. The next option would be to insert the epoxy mass into the assembly, make it a virtual part and save it internally in the file, then go through the same steps after that; this would also work, except that now you've broken the link to the original part file, and the assembly won't update per changes to that part file. 
3. Finally, it would be possible to have each molded shape in the assembly be a different configuration of that epoxy part, but that would be unacceptable per the document control system (configurations are not supposed to be used that way)

What I really need to find is some feature or method that will, in effect, do a mold cavity that is in assembly context – cutting away at the liquid part in places where other parts would intersect – and not interfere with the external part file, yet allow that linked part file to update what is in the assembly accordingly.  It's a tricky situation, and again, it may not be possible, but if someone knows a way, it would be a life saver.

Thanks in advance!