I think I can answer my own question now.
I've tried doing a few "What-If" scenarios in TurboTax. When I am working on my college student's return and answer that they can be claimed as a dependent on someone else's return, the next question is "Will they be claimed as someone else's dependent?" If I answer "No", they won't be claimed as a dependent, I no longer get the Covid Stimulus Credit dialogue. Also, the credit will disappear if I edit a return where I originally said they could not be claimed as a dependent.
