Please help!

My friend has a 4 year old son...He throws epic fits like I've never seen before. He is very particular in he has to open car doors, put stuff in lines, buckle his car seat and if it isn't done his way he makes a huge fit and you have to do it his way or else he just cries. My daughter has never done this...and I've never seen a child act that way and I was wondering if anyone had any advice? It's gotten to the point I hate being around her when he's around...I know there could be a medical issue but she says there isn't. Please don't quote me and no bashing..helpful advice to where I can help her is appreciated.

I have a nephew with similiar behavior issues.

I don't have any advice about it though.

Could be sensory integration issues maybe? My son is like that... here is more info: http://www.childmind.org/en/posts/articles/2011-10-26-sensory-processing-issues-explained