Adding excel sheet to an existing group (not board)

I exported a group from Monday to an excel spreadsheet. I am trying import that same sheet into the same group in the same board. EX: 2024 Board-> Payments-> ABC company group. This group already has various rows and columns, however, i had to add a lot more information hence i exported it to excel to make it more seamless. Every time i try importing this sheet into Monday again, nothing is updating besides for a new group being created.
Thank you in advance!