I have three kids, 2 are over 18 and still live at home, and they did not get the 2 previous stimulus checks because I claimed them as dependents. Removed them/let them go on their own this time, I lost $500 per kid for deductions, but they got to deduct the $1800 they didn't get.

Worked out well I think, plus they should be eligible to get the $1400 in March

Edit: Just to clarify, I only posted this info because there was so much confusion as to what would happen to adult dependents who did not get a stimulus in 2020. I am not a tax professional, so don't take my advice (or others on here who are not tax pros). Everyone's circumstances are different, this is just what worked out for my family AFTER I CONSULTED WITH A TAX PROFESSIONAL. :)