This is something I always wondered because most states require you to be in a marriage before you can adopt a child. I think this is just as much about stability in relationships as it is in finances but that is a different topic. I am wondering what happens to a child who is adopted by a couple if they divorce… Like I would imagine there are people who marry just so one of the people can adopt and they later divorce as a means to “scam” the system.
I believe if it is legal by the state, the child is treated no differently than had the parents had their own child physically. Both parents are allowed to fight for custody, if one should choose not to have anything to do with the child, they will still have to pay child support in most states. As for the scams you mentioned, I believe a couple needs to be married for a number of years before they can adopt which prevents this.
In my state, you have to be married for a minimum of 3 years AND be over the age of 28 to adopt. I am guessing it is set up this way to protect children which makes sense. I think Sara covered it. In most cases, it is handled the same as a biological child but if for whatever reason the state believes the child will be in danger, I believe certain states can remove the child from both parents.