Has anyone been successful in forcing an unwilling person to go to the doctor?

I'd like to hear from you if you have been successful in forcing an unwilling person to go to the doctor. My mother in law is a raging lunatic. Won't go to to the doctor. Doctor has dropped her as a patient for no shows. My father in law refuses to call social services or admit to the police she has a problem. When confronted he broke down and said he won't force her to get help, he's protecting her and he'd be arrested before turning on her. If I call social services can they force her to the hospital if she doesn't threaten them? I've spent hours researching online and it appears that unless she's a danger to herself or others nothing can be done. If you mention it to her she blows up and goes on a two hour rant accusing everyone else of a slew of reasons why she won't see a doctor. We've been going through this for a year and we feel desperate. She needs help. She is psychotic and dillusional. Please don't suggest hiring a lawyer - no funds for that.