I have a form with 4 combo boxes. Box 1 is linked to a unique indexed field of my main table and does not allow duplicates.

Is there a way I can enter selections in the other 3 boxes and save only those 3? (these do not add data, but edit an existing row in the main table)

Experimenting, I found that if I didn't make a selection in Box 1, I could still make selections in the other 3, close (save) the form, and it would make those 3 edits in the table row belonging to the value that was in Box 1.

This is kind of what I want, except that there are many selections in Box 1, and if I select one of them and close (save) the form, I get an error message that a duplicate entry will be made?

Would a possible solution be to have Box 1 on a main form and the other 3 on a subform? If so, how do I set this up? Or is there another way to relate the other 3 boxes to Box 1, and only save the 3.