I believe also that if your child is adult enough to have a child and be unsupervised enough that either you should have custody of that child, because the other parent is not caring for them or child support should stop!
Do I Have To Pay Child Support If My Minor Has A Baby?
In new york do you have to pay support on your child and her baby
Yes, you are responsible for your daughters support until she reaches the age of 18, in California. You are not responsible for her children, though.
Bossman is right. Any child you are the father of, you pay till they turn 18. Any child you aren't the father of is not your financial responsibility.