I've taught 2 dyslexic students in the 12 years I've been teaching. It DOES require a lot of extra work on your part, and, as with many other special needs, you really do need to have a complete understanding of their needs to be able to help them effectively. It seems like her previous 4 teachers didn't have a good grasp, or didn't want to have a good grasp. It's so much more than the notes being confusing for her to read - and for music lessons to work, you'll need to know exactly what causes her difficulty.
I made good use of a forum like this one which you can link too off of
http://www.voy.com/171328/ it's for classroom assistants, but as they are the ones who are working one-on-one with children with dyslexia all the time they are a good resource for questions that are not music specific. It takes quite a bit of reading and research to understand each particular child's difficulties as often not even the parents have the answers.
Of course, if you're not into putting this much effort in, then I would let them know before you start with her and realize that it's too much. It's hard on kids to be bumped from teacher to teacher.