Please have a heart and understand us?

hi, i am writing for my mother. my sister who is 18 was pregnant and never told us anything. all the time with her belly she would tell us it was just her gaining weight from her 1st baby who will be 2 in oct. when it came time for her to deliver she didnt let anyone come upstairs with her. the day later we came up and we were told she had gastric tumors. ok 3 months later from april to july we found out by a medical bill that she had given birth to a boy who she placed for adoption. she had pictures and did not deny a thing when we asked her, but she tried to suicide. she is in behavioral health now and the fam. is suffering. is there anything we can do to revoke this adoption. i know this might hurt the baby and the new parents but my parents were not aware of this and she was under my mother and fathers care since she didnt work. please give me hope. i am drained since i have not been able to get pregnant and lost 2 babies recently as well. help thanks