1040 tax forms

What is the name of your state? NY My son and his girlfriend have been living together for 2 years. She has a daughter from another guy. Can son claim daughter as a dependent on 1040 line 6c and what would the relationship be? Can he claim daughter day care expenses on line 46 and child tax credit on line 50?
Can girlfriend still take the earned income credit using her daughter as a qualifying child? Thanks for help.

If the child lived in your son’s household for the entire year, and if your son provided more than half the support for the child, you son can claim the child as a dependent on line 6c. For relationship, on line 6c, column (3), put lived in household 12 months. He can not claim the child tax credit, because that is only allowed for relatives.

Your son qualifies to take the Child and Dependent Care Credit for the child, if the other tests for the credit are met.

His girlfriend can still take the earned income credit using her daughter as a qualifying child. The child does not have to be her dependent.

He can also file as head of household, if he makes more than she does. The daughter should be listed as a fosterchild, not qualified for child tax credit.