This question doesn't seem to have anything to do with FileMaker Server even though posted in the FM Server section of the forum. The FM Pro section gets a lot more "traffic" and thus poster get more and better help with their quesitons when posted there.
Define a calculation field that combeins the first and last names in a single field. There are a number of possible variations. Here's one:
LastName & ", " & FirstName
Define your drop down to list Resident_Registration_PK as the first field and this calculation field as the second. You can hide the PK number if you want. And you can add this name field from the Resident's Registration table to your layout so that the full name is still visible after you select a resident from the drop down.
Hi-- I tried doing this but the dropdown appears as blank-- however if i use a pop-up menu...it works.
it should work the same with either format. Exactly what options did you specify in Manage | value lists?
Did you specify "text" as the return type for your calculation field that merges the names? It won't work if it specifies number.