So, it seems my assumption that Bella/Kelly pulled Fiona into the mix relatively late in the game seems to be correct.
This gives my assumption that the trolls were composed of two distinct groups some weight, those being the Texas Tech Tween Troons and Fiona, with a likely third group composed of trolls who have been around for a while and are likely already known to us. Now the question is, what did they plan to do at Everfree? Devon's info seems like BS to me, but maybe there's some truth in there.