Help me understand

Hello. My Sister-in-Law has 6 children, and until now, all of them have lived with her. Her 6th child, who is about 18 months old, is now living with her Husbands brother and his wife, and they are in the process of adopting him. I am totaly against this...and not without reason. I was adopted when I was 4 1/2 months old, and I'm glad that I was. I have met my birthmother, and she is a very nice woman, but with her situation at the time, she did the right thing. But with my nephew, I dont believe this is the right thing for him. I question the sincerity of everyone in this situation. My sister-in-law is married, and a decent parent. She is not in any bad situations, except for this, and claims the only reson she is giving this child up is because her hubby's brother and his wife cant have children, ( his wife has 2 children from a prev. marriage, and one does not live with her). This is both her hubby's brother's AND his wife's second marriage, and his first marriage disintigrated due to mental abuse and cheating on his part, ( he was even fired from his job for questionable behavior).Now, my sister-in-law says that she wants her son back. He has only lived with her brother-in-law for about a month and a half. She says her husband "wont let her" get him back. Maybe because he is afraid his brother will be mad? I'm not sure. Also, the people her son is living with have already started to break agreements about how this was to be delt with. Does anyone have any advise on how I can deal with this? I am practically running in circles around my life trying to figure out a way to deal with this.