I also need to update my answer above on the emancipation rule.
Emancipated child. If a child is emancipated under state law, the child is treated as not living with either parent
If the child is treated as not living with either parent, they can't be a "qualifying child" dependent of either parent. However, they could be a "qualifying relative" dependent of either parent who provides more than 50% of their total support, because residency is not required for a qualifying relative dependent who is a biological child. (Total support includes tuition and college expenses but also room and board where they live. Just because the father pays 2/3 tuition doesn't necessarily mean he pays more than half their total support.) They are, however, disqualified from being a qualifying relative dependent of anyone if they have taxable income more than $4300.
I will make a revision above as well.
