My biological daughter has 3 sons that she uses to manipulate her father and me by not letting us see them for 16 months last time. What are my rights?

Mostly your right is any are determined by where you or the children live. What State? The father can go to court for visitation. Most likely he will get something unless there are some adverse reasons he shouldnt.

I think cdad misread the part about the father. You were referring to your husband, not the children's father.

Laws vary by area so we can't really answer without knowing where you are. But, generally, where grandparents rights exist, they are usually for when the marriage breaks up and the parents of the non custodial parent want visitation. So, in your situation I doubt if you have any legal recourse.