@timl, thanks for your answer. I've tried the Lookup you suggested, but I must be getting the formula wrong. The combobox I am working with is drawing data from dbo.Semesters, which has these fields: Semester, AutoID (auto number and primary key). So the only editable field is Semester.
The formula I tried was LookUp('[dbo].[Semesters]',Semester=Parent.Default)
This only partially works because it returns the same default value for all semester records. For example, I have two records: Spring 2017 and Fall 2017. The formula above only returns the value for Spring 2017, even when I edit the record for Fall 2017.
In your example, there was a period and then "Name" at the end of your formula, but I kept getting errors whenever I would add a period and then choose a selction from intellisense.
Can you provide further assistance? Thanks!