If you have either the member name or membership number as the first column entry in each row, and for example the date of transaction in the second column, you should be able to keep the member's data together in a sort, if you sort by Column A first, and whichever column makes the most sense next. But, as said, there may be an easier way to organize your data.

SMITH, BOB 9/1/2022 Membership Fee Paid $2,000.00
SMITH, BOB 11/15/2022 Purchase Gift - Shirt $30.00

etc.