Can you give us more details. How are your siblings contentious and controlling. Explain the unsafe, unhealthy conditions in which your parents live. What is your primary question?
It might be helpful to call a social service agency who can send a social worker to evaluate the living conditions of your parents. In Phila, we have the Mayor's Commission on Aging. They will evaluate the case by assigning a caseworker and appoint a guardian, if need be, which could be you. They will also assist in finding competent health care. It is very difficult to deal with relatives, and some mental illness could be present. If this si the case, I understand the double burden of having to deal with the needs of mental illness and aging parents. Please check out govt services, and we need to pray for all caregivers! We do a valuable job and are the least appreciated of any segment of society.