ds 160 travel companion

applying for B2 visa for in laws in USA. While filling the form for brother in law, there is a section called travel companions, where I am putting the name of father in law as his father, but when it asks for relationship with person what should i put, child or parent?

Well, you need to put the relationship of the person to the other person traveling along in the group. If something does not exist, you should select relative. I recommed that you check out US Dept of State DS-160 Guide