Oh and another quick point for your friend to consider - even if she is a highly experienced, confident, professional trainer (which I am very much doubting). It's all good and well to say you've 'trained' the horse 'not to rear'. But in my books, once it's been a chronic rearer, it will always revert to that habit in times of stress, panic or discomfort. Even if the horse has an issue with your contact on the bit, it should not rear - unless you are of course, giving it no other option I.e. Pulling back so hard that it's chin's on it's chest, while kicking the hell out of it. Then it's got no where to go but up. Otherwise, rearing is straight out dirty. My guy has a nasty habit of jacking in front, if that jack turns vertical, he will be off my property before he can take a breath.