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."
It is clearly TWO "tax families".
For purposes of the PTC, your tax family consists of the following individuals.
You, if you file a tax return for the year and you can’t be claimed as a dependent on someone else’s 2019 tax return.
Your spouse if filing jointly and he or she can’t be claimed as a dependent on someone else’s 2019 tax return.
Your dependents whom you claim on your 2019 tax return.
(d) Family and family size. A taxpayer's family means the individuals for whom a taxpayer properly claims a deduction for a personal exemption under section 151 for the taxable year. Family size means the number of individuals in the family
We all conclude that a father and a daughter can’t decide to allocate all of this credit to the daughter’s tax return.