My fiance has full cusody of his 4 children. The birth mom abandoned them and was out of their lives for about 2 years. She then got visitation rights a few months ago. She is supposed to visit with them every other Saturday from 10 am - 4 pm but often cancels or shortens the visits. She is an alcoholic and prescription drug abuser in deep denial. She is supposed to pay a miniscule child support payment once a month but even with the garnishment it's not much because she only works part time. She does nothing for these kids. I have already become like a mother. If I could adopt the kids I would, but the birth mother would never go for it - to her, the kids are things she owns. Is there a way for me to become a legal guardian instead - once we marry? Do we need her permission?