So I went to the head coach yesterday & explained the issue to him - he told me that he doesn't use them very often (for his level 5+'s) but it seems that the level 3 & 4 coaches really like them and even though he's told them it's not a good idea they continue to use them. He did not, however, seem to agree with me that they were a safety issue & said that he thought they only cause problems in extreme situations - hmmm :-/
I told coach (the level 4 coach) that I didn't want her to use them any more as they were causing back issues for her - the coach was NOT happy about this but agreed to let her not use them "for a while".
Luckily, it's only 8 more weeks until move-ups and then she'll be with the head coach. I do have to say that I'm a bit confused, if the head coach doesn't want the lower levels to use the weights, why doesn't he just tell them not to... he is the head coach after all!??