I inherited a workbook which uses a table to sum worksheets together. I
understand how to update the table (which is in its own tab) to accommodate
worksheets I insert into the current workbook, but I do not know how to
transfer this knowledge in another workbook I am creating. The formula in the
cell:

=SUMPRODUCT(SUMIF(OFFSET('Sum Table'!$D$5,ROW('Sum
Table'!$D$5:$D$24)-MIN(ROW('Sum
Table'!$D$5:$D$24)),),1,INDIRECT("'"&SName&"'!"&AD DRESS(ROW(D18),COLUMN(D18),4))))

What should I do in the new workbook to get to the point of using this
formula? I have tried to duplicate the tab and the table, but still no
success. The workbook contains about 20 tabs that need to be summed together
in a number of different ways. I am trying to avoid doing the sheet1+sheet 2;
and because the sum tabs overlap I cannot not put the sheets in groups.
Thanks