My advice is - have 2 data entry sheets with a single table on both of them.
1. a sheet with table, where all Mod's are registered;
2. a sheet with table, where all WorkCards for all Mods are registered - with a field for MOD in every row.

And then you need a report sheet, where at top of it user can select Mod, and the table of work cards for this Mod is displayed - either using an ODBC query from Work Cards table filtered by selected Mod, or using formulas which read matching rows of data from Work Cards table.

And you of-course can have any number of other report sheets to get any other info you need.

The bonus of such design is, you can add new mods or new work cards at any time there will be a need, and no redesign of workbook is required!