Let see if I can explain this. Let's say I create a part andcall it "P1", if I go to that parts property box under the customtab can I put in a string that will automatically populate the"value/text expression" box with that file name (without the.sldprt extension)

I know you can do something similar in the drawing sheet format"SW-File Name" but this needs to be done in a part box as atemplate.
SolidworksParts And Features