Thanks again to all the experts who replied on this thread (even though I didn't start it). The turbotax community is incredible!
I emailed the MD tax helpline about what happens if a child is a dependent but not claimed on the parent's return. This was the response I received today:
Thank you for contacting the Comptroller of Maryland.
If the dependent is not claimed on the parents’ Maryland Form 502, they may select the “Single” Filing Status (if that applies to them). If the dependent is claimed on the parents’ Form 502, then the “Dependent taxpayer” Filing Status (Box 6) would apply.
