agtover'sCredit to agtover who provided the solution in a comment to the question works fine: Extend
I extended the function range to include D3 (wherewhich contains the column heading 'Amount' headline is)which the SUM function ignores.
Using =SUM(D3:D101)
, and then wheneverwhen a new row is addedinserted above D4, only the end of the function range is updatedin the formula expands down and includes it: =SUM(D3:D102)
.