my dependent is trying to complete his return and keeps getting errors. He is covered under my family HSA + HDHP and does not have any other plans. if he doesn't say he had an HSA then it says he had a lapse in coverage. if he does say he had one with no contributions or expenses it complains he should not have checked family on 8889-T worksheet for each month in line 3 or that he should not have selected self-only on those lines depending on whether he selected family or not in easy-step.
what is is supposed to enter?
A dependent is not eligible to contribute to an HSA.
He should not have indicated that he had an HSA. BTW, there is no such thing as a "family HSA". Each HSA is owned by an individual, i.e., you or your spouse.
"if he doesn't say he had an HSA then it says he had a lapse in coverage. " This comes from the question, "What type of High Deductible Health Plan did [name] have on December 1, 2020?"
Your dependent should answer this one as NONE.