I'm getting push back from the CPA that is preparing the father's tax return. Here is what he wrote to me:

"While it stinks to have to pay back the premium credit, I’m not willing to sign a return I’m not comfortable with. The premium credit is an advance for people who can’t afford the premium. When the income exceeds these thresholds, it’s taxed (as was done on Ryan’s 2018 tax return)

Perhaps you can continue to send me information that will give me that comfort about changing the way we prepared this return, but my team has taken a long look at this. We all conclude that a father and a daughter can’t decide to allocate all of this credit to the daughter’s tax return. That’s not the intent of the “tax family” allocations which are normally between divorced couples, etc..

The Form 1095-A shows that all four (Ryan, Alexis, Andrew and Haley) were covered by health insurance and the 1095-A is in Ryan’s name and social security number. I know no other way to proceed on this without triggering an IRS notice about not properly reporting this under Ryan’s social security number.
We don’t think this example applies – they are not a two tax family. The example under that situation is based on divorced parents – each parent is its own tax family. In this case, Alexis is filing her own tax return but that does not make it a two tax family for purposes of the allocation."

Do you have any further thoughts?