Most biomorphs are either internal or so similar to the existing shape of a nid that most opponenets cannot tell what they are when - most of the time a well written army list, codex and a statment as you put down each unit as to what it is armed with are fine. Most people don't know many upgrades past the armies that they play at - and be carefull with tournaments, if you want to know if you can get away with something don't just phone in and ask (you just get the stock answer of yes - someone once got that for scuttlers!) If you want take some photos (clear ones) of the models in question and state clearly the biomorph in an e-mail - hopfully they might read it through
