we have joint custody the mother has lived with serveral men. I want to file for full or physical- guardian custody. I feel the mother doesn't know what is best.. I am not trying to take away their relationship. But want safety for my child. She (the mother)does have full custody of a 2 yr old from a different man who went to jail. My child is 6 and has seen many things that 6yr olds should not see. Could I lose the joint custody I have now - if I file for full or physical and don't win?