As I think I noted before, all 4 of our children have split from home. We had hoped the youngest would avoid some of the troubles, but the pull of a messed up life was too much for her and she is now facing things as an adult, with very minimal contact with us. This is hardest on my wife, who had a fairly close relationship with her, but it is still tough with me too.
You don't go into this expecting to end up with nothing. While they are all better off than they would have been if they were left in the system, none appears to have a close bond to us now. I don't think they have a close bond with anyone right now, and that is ultimately more harmful to them.
We do have my daughter-in-law and granddaughter living with us for a bit more, while my oldest son completes basic training with the Army and possibly his advanced training. That has pluses and minuses. While I am glad to help them out, I also want to make sure I am really helping and not enabling. And while my wife and I want basic ongoing contact (such as phone calls), we are looking forward to a mostly empty house with just the two of us.
Many people tell me that they will "return to us" at some point, at least in the manner of having a relationship. I even had someone at a job I just left tell me (she was adopted at birth) that the birthfamily relationship loses its luster over time. I have a harder time keeping out hope for that now, but hopefully they can get over the past and we can rebuild a bond of some kind. Ironically, they are very unlikely to bond with the birthfamily if they can't bond with us. Even though I believe the birthfather would be happy if I was totally gone, his best hope for a strong relationship is if they can strongly relate to me as well.
Unfortunately, he is stuck in the "regain my family" mode. I don't know all his motivations, but it seems that this makes him much more hostile than he needs to be. It has caused him to do some strong lying and breach our trust of him, but he feels justified for his actions, so he is not sorry at all.
Long road. Think and pray hard before marching down this path, especially if you are adopting siblings. Many parents may be needed, but many parents are also rejected. Hopefully my experience is just an anomaly, but I don't think so and those pushing adoption really need to factor in the long term, not just the need, however great. I don't know that most people are ready for this at all.