How to get support for adult daughter after my death

hi my daughter is 32 and lives with me (mum) she is autistic , Asperger’s as well as moderate learning difficulties. A social work assistant said years ago my daughter presents better than she functions.
so while she appears capable, life for her is really a struggle. She makes poor diet choices , poor hygiene choices , cannot retain information and worries constantly about not being able to process information and then gets very emotionally overwhelmed and breaks down and cries. She works two days a week but has lots time off. Her employers are good as she works in college for kids like her.
Her sister says she cares about her but does not understand the effects of her autism on her life. Her father lives in Spain with his knew wife and again does not accept Rosie’s needs. He openly says he doesn’t believe in special needs. Rosie does not want to live in Spain with him. How do l get help in way of sheltered supported housing for her when I’ve gone . We asked for needs assesssment but SW who came to us said they could find no proof of her autism diagnosis despite it being in her medical notes. We printed off copy from GP and still not believed so l threw women out in frustration. How can l make authorities understand that she will need a lot of support and just because they can’t see it she really does have support need when l am no longer there to help her. Sorry to go on any advice appreciated

Jane