Workbook within a workbook

[gogreen]

I'm working in Microsoft Excel for Mac version 16.16.27. I have workbooks within a workbook consisting of different grouped lists of items. Right now each row is numbered sequentially throughout. I'd like to restart the numbering for each list--that is, I want to go back to "1" with the start of each list's rows. How do I do this in the single workbook?

Like this:
Xxxxxxxx (heading)
1
2
3

Xxxxxxx (new heading)
1
2
3

Xxxxxx (new heading)
1
2
3