DFF for Budget Entry

We need to segregate our budget amounts by Fixed and Variable. We added a new segment to the COA to do this, but this is causing inquiry problems - we cannot see, budget to actual on the inquiry screen since actuals aren't broken out by Fixed and Variable. I had originally thought the best was to do this was to set up a DFF on the budget entry screen to capture the Fixed or Variable Component of the budget, but there is no DFF available.  Does anyone have any idea how I might be able to accomplish this breakout for budget short of customizing the