Import Question (linking tables)

I’m working on moving my old Contacts table and my Cases table into SuiteCRM.
I’ve successfully exported these two old datasets into CSV.
Now I’ve got two big spreadsheets (50K rows, ~100MB each)

The import into SuiteCRM goes pretty well.

The problem I’m having is this:
I can’t connect Cases to Contacts because there is no Account Name in the Cases spreadsheet.

The two spreadsheets have one field in common; a numeric ID.

I’m hoping someone can give tips on helping me map the fields so that each Contact displays the Cases associated with it.
(I’m hoping that I don’t have to rename every ID in the Cases spreadsheet.)
Thanks so much. :slight_smile: