A button script should work... but why?  Bill Maintenance is where you configure recipes, not enter transaction data.  Why does QoH matter on that screen?

If you are using this screen as you plan production, a report would be much easier to work with.

Would be a lot faster and easier than running a component requirement report. 

Would be a lot faster and easier than running a component requirement report. 

I'd say QoH would be incomplete (where Available is the number that matters... yet is not stored in any table), and constantly at risk of being stale (as other transactions are posted), but you know what you want.

I'd do a button script to loop through components, with pop-up of list of numbers, instead of trying to put the values in grid fields (where you run into grid display refresh issues).  The quantity values are point-in time, and a pop-up should always show real numbers for each click.

An Excel query can do the same thing, with more values listed... and a simple Refresh All to bring in current numbers.