Thanks for the suggestion Karza, I think I might do that!
The only problem is she lives interstate and can't afford to pay for her own hair trials, but the hairdresser I've been speaking with has been pretty understanding and helpful. My sister sent me pics of what her hair looks like atm so I can show the hairdresser when I have my trials, so I'll ask her then what hair styles she suggests.
(My sister reckons she saw a hair dresser the other day and the hairdresser suggested that she keeps her hair down and straight?! I can't say I've ever heard of a professional giving that advice before?!)
The BM's are getting away with everything pretty lightly (I'm paying for dresses, MUA and hair on the day, they can choose how they want both, they can choose their own shoes, I bought them jewellery as a present) which makes it a little frustrating that my sister's being such a pain and putting on her "poor me, poor me" attitude again!
I have said to all of them that they are free to choose how they want to look because their going to have to put up with it all day and I want them to feel comfortable as well!