DS160 help for minor's H4

[AM12345]

I am filing ds160 for my minor son. In the travel companion question, for the relationship part of my son and his mom, should I mention child or parent(confused as the question is not clear if its asking how my son is related to the companion or how the companion is related to my son)?
Also, for the person paying for trip, will I be counted as US petitioner( I am on h1B), Relative, or mark it as Other?