How do you deal with an adult who doesn't find a job and lives off of family?

There is such a person in my family. She trained to be a nurse and worked as such for awhile, but then she began having problems and was diagnosed with schizophrenia. Our parents took care of her and she makes periodic attempts to work, but the illness overwhelms her when meds need to be adjusted. I’m not sure what will happen when our father’s gone. 😞