What's your current temporary custody arrangement?
Why have her parents taken in their wayward daughter? I ask this one because I wouldn't take in my daughter in the same situation. I'd send her home to her husband (who I gave her to on their wedding day) and tell her to work it out with him, dump her OM and quit her job at the hospital. I'd also probably make my own visit upon OM telling him to get away from my family and hurting my grandchildren. I'd 100% support my son-in-law after accessing the real facts of the situation to the best of my ability (hopefully discerning what is real and what are wayward lies in the process). Why are her parents enabling her??
The internet is 90% complaining and entitlement and I hate it because I deserve better!
