The county that I live put a lien on my son's birth father for real and titled personal property for back child support owed to me. BF and his wife are now in the process of getting a divorce. They own a town house together, but I do know that the wife put the down payment on it and has been paying the mortgage on it. I also know that she will want the town house out of all this. Will this lien on BF affect their divorce?

I have no contact with either of the two so I can not discuss this with them.

Since they own it together most likely if she goes to sell it or the Judge says they have to sell it and split the money his half should go to pay on the lien.
It is possible if she proves she put the majority of the money into it he may get less than an even split.