I want to adopt my husband's child

Hello! I haven't posted in here before, but I had a question that I thought someone might be able to answer! My husband has full legal custody of his 2 year old daughter. His ex-wife has visitation 3 weekends out of the month from friday evening until sunday afternoon. She is a dead-beat mom but seems to think that she has just as many rights toward the child as my husband even though she is the non-custodial parent. My husband would like for me to be able to adopt his daughter. Does anyone know if this is possible to do even if his ex-wife has visitation time? Like I said...she does not have any custody over the child. ( I know..it's a strange case.) It's really hard to talk to parenting coordinators or lawyers about it, because it seems that they are all for the biological mother..even though she has no custody, never showed up for court when the custody battle was going on, and is just a dead-beat mom. Any suggestions???