Hey there everyone!
I've had this theory stuck in my head for a couple weeks now and I wanted others opinions on the subject. For starters, I got this theory while watching a video by this guy on YouTube called EruptionFang and I recommend you watch the video I'm about to mention. In short, the theory video was about Yatsuhashi of Team CFVY possibly being an undercover member of The White Fang; specifically the Lieutenant Weiss fights on the train.
Since I recently re-watched the series, I've been wondering if perhaps Velvet is possibly an undercover member of The White Fang too and we just haven't seen her in uniform yet. Believe me, I would certainly not want this to be true as Velvet is my favourite character in the show. She uses her weapon to copy others weapons and her semblance mimics the movements they use with said weapons. Think of how useful that would be to The White Fang. She could be one of their best soldiers using this strategy!
However, I also wonder if perhaps all of Team CFVY are members of The White Fang (Coco and Fox just hiding what their Faunus trait is. Blake did). Think about it, they might not have all been on the train so the rest of the team would've just needed to wait for Yatsuhashi to run a few blocks to their ship and arrive to help out Team RWBY with the Grimm. With all the said though, the one hole in this theory I can think of is Professor Port. He's on the ship with them but he's loyal to Ozpin so it's a pretty big issue with the theory. Maybe it was a robot similar to Penny while the real Port was elsewhere?
So, what do you guys think? Could Velvet possibly be in TWF? Maybe even all of Team CFVY? I'd love to hear your thoughts on this theory.