Reqarding child custody and abandoment, my sd has been living with her dad and myself for 5 years now with no financial support from her mom, except medical insurance provided by her step-father. She just dropped her off at our house one day and said she could not handle her anymore and we have had her eversince and dropped child support my husband was paying immediately. She only visits her mom occasionally on weekends. Now her mom and her husband are trying to talk sd into moving back in with them. SD is now 13, what are the chances of her regaining any custody after all this time? They are telling her it is all her decision and the judge will let her live where ever she wants to live. Can we really lose her after all this time?

I hope someone with more information can help you, this is above my area of knowledge.
But I do think it would help to know what state you are in, as laws vary state to state.

And are there any legal documents or court orders in place for your step daughter living with you and your husband.

Also please try not to use the SD, and other abreviations, it confuses a lot of people not familiar with that :P

First, ANY question on law needs to include your general locale as laws vary by area.

However, in no US state can a child make such a decision. That decision is always up to a judge. Some states do have guidelines on how much weight to put on the child's preference. A 13 yr old will be listened to.

Abandonment is not an issue here. But what you don't say is what court orders are in place. When she was dropped off, did your husband go back to court to modify the custody order?

We are in NC and other than origonal papers when she was a baby, there have been no modifications. So that leaves me to where does my husband stand legally as a parent since her mother just left her with us. She does however see her some weekends, but other than providing health insirance, provides no other support.

This is a serious issue, since you will still owe child support if there was a court order, if no one went to court and actually modified the agreement. And the ex who ( does not have the child) can still collect and ask for back support, from the parent who physcially has the child.

This happens every day and even I got caught up in this for 3 years of support on my boys when they were young and their mom dropped them off at my door.

And yes, at this point the mom can legally claim she still has legal custody ( and does if no one went to court to change it)

So you need to rush to an attorney and start the legal ball rollling.

Seeing her some weekend and proving insurance is considered legal contact so there is no abandonment at all that can even be used.

Mom has good standing right now to ask for child back and force it in court, so you need to get that legal custody changed.

Also there is another issue, if you had done the custody change when the child moved in, the child was too young to testify, at 13 most courts will allow her to testify where she wants to live ( can not just move back and forth)
So if the 13 year old testifies in court she wants to go back to mom, you could well lose the case and mom retains custody, and you pay 5 years of back child support.