Legal question about medical rights?

Is there a way to legally take control of disabled parents medical decisions if they are willing to stop other family members from making these decisions without including parents or family members in them? My brother went behind my fathers and my back and had my mother baker acted. He did not include in this decision, and did not tell us about it. We sat at the ER all night after we called an ambulance to pick her up cuz she was in diabetic shock. We were not allowed to see her, and when we would ask what was going on we were told that "due to the cirstances she was admitted under" we were not allowed any information. She was not violent or suicidal or anything when the paramedics picked her up. We told the ER nurses that we are the ones who had her admitted and still they would not tell us anything. After fighting with them the next day, we were finally able to see her, but not without a sitter, and she was restrained to her bed. We didn't understand, and Again were told it was for her safety and they could not tell us more information. At this point she was pretty much incoherent. On the third day, my mother called my father and wanted to know why he had baker acted her. We were not aware of this. When we went back to the hospital, this time she was coherent and told the nurse that we were to know her medical information and we were able to make her decisions. That is when they finally explained that my brother had baker acted her, that she was restrained to keep from harming herself, and that the sitter was there because she was on suicide watch, based on information my brother gave them. We want to find a way to protect ourselves so that he cannot go make desicions for her without our consent. I am 28 years old and they are both disabled. Is there a way I can become thier medical surrogate or something, so that any major medical desicions cannot be made without my consent? Or a way that we can legally require the consent of either the patient and 1 family member, or the consent of 2 immediate blood relatives before any major medical desicions can be made? We just want to insure that all desicions that effect the family are made by the entire family, not just someone looking for the easiest way out. Thanks in advance for any help.