You have gotten some great ideas. I very strongly recommend reading (and using) Parenting Your Child with Love and Logic by Faye and Cline. If you go to their website you can see all the different books they have. many are available in audio format as well as print format. The website has quite a bit of stuff on it, and be sure to check the stuff for teachers - those ideas can help at home too. They have some great tools to help with problems like this.
I also suggest looking into sibling abuse. there are books on amazon that you can find that can help you understand what is going on and how to stop it and help them. Like children abusing their parents, sibling abuse is almost completely ignored in most countries that I am aware of. I learned about as we were dealing with the EXTREME abuse Wiz was heaping onto Jess. It helped a lot, not just with my kids. It also helpe dme deal with issues from abuse from my bro in my childhood. I was pretty shocked when even the excellent very experienced therapist we loved had not heard of it. Luckily, many of the things you have already done and have been suggested are things that will help.
I have spoken with people who SWORE that L&L did not, could not, would never work with kids on the autistic spectrum. This was before the version written for sp ed kids was released. that surprised me because it was working quite well with Wiz and thank you's teacher was having great results with two little boys in his class (who are on the spectrum). the results are not immediate and you don't have to take the immediate action that other plans insist on. in my opinion L&L treats children as though they have a brain while many treat them on the level with puppies. I got so SICK of books that said that if you did not deal with a problem right when it happened, or within about an hour, then giving consequences or punishments was futile - that consequences/punishemnts MUST be immediate to work with kids in elem school and under. L&L has the OPPOSITE approach. One example is a 4yo who calls his father a "po0pie head monkey-tush" one Tuesday afternoon. Child knows it isn't okay and is told to stop. Child continues. Dad does not react.
Dad and son have a ritual on Sun afternoon that they go out for "guy time" and get pizza and play video games. So Sunday comes and the time they leave is here and the little boy goes and tells Dad that it is time to go, why isn't he ready?? Dad tells son that he doesn't want to spend special time with someone who calls him names. That isn't fun for him. Maybe next week or the week after they will go for pizza when Dad isn't expecting son to call him mean names.
The name calling doesn't become a drama at the time. Dad doesn't lecture, whine or even give consequences at the moment. But when the fun time is supposed to happen, the c hild gets a totally natural consequence - Dad won't take him because Dad doesn't want to spend time with someone who calls him names. NO ONE tells the child that name calling is bad, that he isn't allowed, how it hurts, etc.... the delay in the consequence makes it even MORE effective because it is a TRUE logical consequence.
It is SO FAR from the normal advice for kids calling names, as least as far as the books I have read.
Another technique for unwanted behaviors (not from L&L) that you might be able to adapt to the situation is to make them do it until it is no longer fun or shocking. I learned this from the director of the Montessori preschool my kids attended. If a child spat on someone, he got a dixie cup with a line drawn about 1/4-1/2 inch from the bottom and they didn't get to do anything fun like recess until they filled the cup up to the line with spit. they had to carry the cup around as they did things in the school too. When thank you insisted on jumping on the bed it took working from 1 min up to 5 to get him to stop for good. And when Wiz thought calling me a b****'ing F***ing Wh*** in the middle of a store he was NOT amused to find me insisting he say it over and over and over for 1 min per yr of age - and he was 10. I insisted he was not to say the words but to SHOUT them. He didn't say much for the next three days and he did not EVER call me that again.
I am not sure how to make it work with the teasing, but I would think having daughter pretend sneeze or cough for 1-2 min straight (to start - work up to more time until it ends the issue) would make that a very unappealing thing to do. It SOUNDS easy, but just sit in a private area (the bathroom?) and try saying anything, or even just making a fist and releasing it over and over for a minute. You will realize how long it can be - and how tiring it can be to do cough, sneeze, squeeze and release a muscle, etc....
