Who can get guardianship

My 18 year old son refuses to take his meds for his bipolar. He walked out of the house on July 18th 2014 and doesn't want to come back because he refuses to live under our house rules. He's been arrested for shoplifting, he's dating a 15 year old which is against the law. He moved in with his biological father who no longer has parental rights since 10 years ago when my now husband adopted him,. His biological dad now wants guardianship so he can enroll my son into school because he said a GED is not good enough, he also drives my son to see and spend weekends with the 15 yr old. Question is, as parents can we take our own son back to court to get guardianship over him so he can get in the hospital and back on his meds, and stop him from seeing underage girls?