Can some assist me please?

I have a small spreadsheet with 22 rows in it. I want to be able to add an
additional row with formula when any value is put into the last cell which is
d22, adding a row below it will then off course will make the lastcell d23
and so the routine will be triggered again. The spreadsheet has formula in
cell c22 which would need copying down.

Any solutions would be greatly appreciated, I hope I have explained what I'm
after!

Thanks


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Mark