Can I enter 1095-A allocation amounts for my shared marketplace policy that will benefit each of us w/ a refund? Why is the result different when SLCSP is left blank?

[kmm24]

(Please see edit below.)

I share a healthcare marketplace/ACA policy with my daughter who is no longer my dependent and I pay the monthly premiums. When she became independent I did not remember to change her status during the ACA re-enrollment period to no longer being claimed as a dependent on my taxes. 

So I'm worried about allocating the policy amounts in an above-board way. We have experimented with entering numbers and if she enters 0 each for Premium, SLCSP, and APTC on her form, she doesn't get a refund and doesn't have to repay. Fine. If I enter 100 for each, I owe $1500. Ouch.

She made far less than me last year, so if we do the reverse and she puts 100 for all three, she gets a refund (yay) and if I put 0 for all three, I don't get a refund and don't have to repay. Fine.

On the other hand, if we split it evenly and she puts 50 for all three, she gets a smaller refund. If I also put 50 for all three, I owe $1500. BUT - if I leave SLCSP blank and put 50 for Premium and APTC ONLY, I get a refund! I'm so confused!

(EDIT: there are amounts in all three columns A, B, and C on my 1095-A. Does that mean I'm required to enter allocation amounts for all three or can I leave SLCSP blank?)

So my questions are: 

1. Is it okay if I leave SLCSP blank on my form to get the refund or am I required to put a number in that field (which would force me to repay)? It seems like splitting 50/50 with my SLCSP blank is the better option for both of us.

2. Is it okay to enter numbers that will only benefit us even though I neglected to change her dependent status during the ACA re-enrollment period? (I will correct that with my marketplace ASAP.) Is it not cheating?

3. Why is the result different depending on whether SLCSP is filled in or not? I noticed on the "How do I figure out these percentages" link window that pops up that SLCSP can be left blank only for certain situations. This question is less urgent as I'm only curious. 

Please help 🙏 and thank you to whoever can!

[kmm24]

Update: Ya'll, because this portion of my tax return with Turbo Tax was so opaque and confusing to a lay person like me, and the dozens of answers I read by the "experts" in these community Q&As only offered unhelpful, simplistic variations of "the IRS only requires that you enter values equaling 100%", I gave up and went to an in-person tax prep service. I was so relieved to snag an appointment with them in the final weekend, and I'm very glad it's over and done. Long story short, I was not allowed to leave SLCSP blank so I ended up putting 100 for me and 0 for my daughter and paying the $1500. But at least I got answers and help from a friendly, efficient, real person sitting in front of me, instead of stressing at home in front of my computer.