It sounds like this isn't an option, but a couple of formulas:
=IF(OFFSET(UniqueNDCs,ROW(1:1)-1,0)>0,OFFSET(UniqueNDCs,ROW(1:1)-1,0),"")
and
=SUMIF(NDCRange,A2,IASTQTY)
Since that isn't an option for you, a bit of VBA. Go to the VBA IDE (alt-F11), insert a new module, and paste in this code:
Public Sub CalcTotalQty()
Dim rngStart As Excel.Range
Dim lngRows As Long
Set rngStart = ThisWorkbook.Names("UniqueNDCs").RefersToRange.Cells(1, 1)
lngRows = ThisWorkbook.Names("UniqueNDCs").RefersToRange.Rows.Count
rngStart.Offset(0, 1).Resize(lngRows, 1).Formula = "=SUMIF(NDCRange," & rngStart.Address(False, True) & ",IASTQTY)"
Set rngStart = Nothing
End Sub
All it does is put the formulas in for you. It assumes the named range UniqueNDCs scope is Workbook, if it is tied to a worksheet then it will have to be tweaked a bit. If you want hard values instead of the formulas, just add a line after the autofill:
rngStart.Offset(0, 1).Resize(lngRows, 1) = rngStart.Offset(0, 1).Resize(lngRows, 1).Value
You can associate this with a button on your sheet, I think you have that part well in hand. I assume you have a dynamic range for UniqueNDCs, something like:
=offset(Sheet1!A2,0,0,counta(Sheet1!A:A)-1,1)
So when you add/remove items the named range still reflects the correct range?