A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
In cell H4, enter this formula
=IF(A4="","",SUMIF(A$4:A4,A4,G$4:G4))
and then copy it down through row one beyond the last client.
When you insert a new row for an existing client, copy the formula in column H from the row above the new one.
When adding a new client, add two rows and copy the formula to both. Then leave the first row blank and store the client data in columns A:G of the second row.