Urinating & Deficating in Bedroom

I am the adoptive mother of three children who were abused physically and sexually in foster care. We have been able to manage most of the behavioral challenges by disciplining "out of the box'. I am looking for input from anybody out there who has experiences dealing with a child urinating and deficating in the bedroom. The children are 9, 7, and 4; and have even gone to the bathroom into the heating vent. Their bedroom is 3 feet away from the bathroom. I know that there was some abuse which occurred in the bedroom and bathroom, but we are struggling to get past this. I am having to replace the hardwood floor in one bedroom because it has warped. Can anybody share any ideas? Thanks so much.