Can I add comments to my file or have UpSheets ignore certain rows?

Yes. UpSheets ignores any row where the first cell is empty, and any row where the first character of the first cell is # (without the quotes).

Ignoring rows with comments or calculations

If you have calculations or comments in your spreadsheet that you want ignored, put a # at the start of the first cell in that row. The row will be ignored when the file is validated.