What can I do if now my father is keeping my children from me?

We need to understand what you did to give my parents guardianship of your children. If you just signed a letter that was prepared by your father that says you were giving your parents guardianship and there is no court order signed by a judge, that is not good enough to grant guardianship to your father or both of your parents. In that case you should see a lawyer or call the Oregon Department of Human Services in Bend and tell them that you parents have wrongfully taken your children.