Did you have to go through the paperwork to have the home declared as section 8 housing?That is the approach we took with my parents. We owned the home and leased it way below market rate to them. It worked out great but they wanted to live near a military base to capitalize on their retire benefits so it was not close to us. Once it was just my dad, he moved up closer to us and pretty quickly moved in with us.
I know a couple of our friends have purchased condos for their children with disabilities. In order to not affect the child's SSI/SSDI and to be able to charge under market rates, they had to get the condos declared section 8 housing. One mother had her basement made into an apartment for her daughter and she had to have the basement declared section 8 before she could rent it to her.