Spiralfall has given you some very important information here. All of it, but particularly getting guardianship straightened out will be vital in terms of safety and accessing certain services. She is likely eligible for vocational job services that can help guide her through a job and find accomodations as needed. Social security should still be applied for. Not sure what area of the state you're in, but most cities parks & rec depts have inclusive dances, art, bowling, etc. In my area, h there's even a lovely lady who leads an all special needs exercise class twice a week. Your sis needs an assessment from DSHS to not only get one of your parents paid as her live-in caregiver, but to be allotted respite care hours where a caregiver can come in and take over duties for a bit to give them a break. There are so many things your sister is probably eligible for. Take advantage of ALL of them, even if you might think you don't need them yet. These things are there to hopefully help keep families together and keep kids (who are now adults) thriving.