The main idea would be to allow each model state to have a separate manually entered mass that could be entered in the model state spreadsheet just like any other iProperty. If you needed one part to auto calculate and others manually set you would set a mass of -1 for that row (because that's how iLogic turns a mass property back to auto.)
Some background.
I need to create part files that represent a family of purchased parts. I don't need the internal parts just something that looks pretty, occupies the right amount of space, and represents the actual mass. I like model states over factory members because they retain named faces/edges. I just found out that if I override the mass for one model state it changes them all and doesn't add a column to the MS spreadsheet.
Below is the link to my forum post about the same issue. If you have a good work around please check it out.
https://forums.autodesk.com/t5/inventor-forum/manually-set-mass-for-each-model-state/m-p/12228289/hi...