help working with annoying parents.

ok. so im sure that my friend's parent's have a reason for behaving the way they do. but hell. they dont half make things difficult.
my friend has been diagnosed schizophrenic. i believe this is wrong, but i cant really change his DX myself.
his parents are undeniably trying to force him into a certain path of life. they control any money he would get from EMA, (education maintenence allowance) which is HIS money. his father is also effectively taking his car, which he has to pay for.

his parents dislike me being his friend, and can only just tolerate his girlfriend and another of his best friends. i believe it is quite isolating for him. i believe they dislike me because i am female and she is aware (due to my stupidity) of my SI. i think she thinks im running some silly cult or something. and im going to harm my friend.

i believe also his younger brother is getting favouritised treatment. money being spent on him and stuff like that. this is unfair when my friend is made to pay for EVERYTHING he gets, and is being pressured into possibly leaving the 6th form and going straight into a job. this is NOT a good career move. i know this myself. im sure his parents should have realised this too taking the same route.

my question is how can i A. get his parents to accept me, and B. get his parents to loosed up on him, WITHOUT screwing everything up, and causing them to assume im interfereing little girl who doesnt know whats going on. truth of the matter is, i know more about this boy than his parents. and they dont like it. its incredibly irritating that parents sometimes assume that because you know or act like you know more than them, you are going to look on them as bad parents.

yick. if anyone has any advice, please help. im bashing my head against a brick wall here. if i was his mother everything could be done. but because i am simply a teenage girl, i cannot affect his life in any way.
its reeeeeallly worrying me now. because he is starting to consider suicide as an option. and that is not acceptable. yeh, call me selfish, i dont want my best mate to die. is that so bad?

halp

Be a friend in the best way you know how. Avoid trying to change the parents. Be steady. Anyway, those are my thoughts of the day.

Selfy ,, my little friend ..... old saying of wise words : Pick your battles if you want to win the war .

i figure if i let his mom get to know me she might relax a little and realise i only want to be good to him.
his dad however....
he is unchangeable. he will never like me. he will always think im bad. its kind of depressing. i dont WANT to look bad because i dont want to do anything bad and i just want beav to be ok. iono. ill stick to trying to make his mom realise i would never want him to do what ive done to my arms and **** them up entirely. that would be awful. i do believe that his mother has a logical reason to distrust me, something beav said about someone she knew i cant remember. but thats fair enough you know? as long as shes openminded enough to try and accept that im not a cult ***** who wants him to commit suicide or hurt himself or anything else equally horrible.
ill see if i can work with them. or try. at least. i dont want to come across as the annoying know all kiddie who thinks they know best for my friend. yes i know alot, and i think i know what should happen to help him, but they would never accept advice from a 16 year old girl. who would? especially if they didnt know this kid.
its just incredibly frustrating as i feel like yet again, my age is letting me down. dont get me wrong i love being a kid. but its a PAIN to see something not going the way it should. simply because of typical human pride. pride annoys me. it gets in the way of things.
but im rambling now. so yeh.
thankyous guys