I think this is quite possible. We know now Misty is afraid of Tommy because of the RO, imo. If her family was involved without her direct knowledge, it could be she suspected it and why she pointed the finger at the cousin to begin with early on.
I raised this possibility recently and was met with a lot of resistance, but I still think it is no coincidence her brother was at the mh that day after Ronald left, lives in the mh park within walking distance, and the rest of it, imo.
LE is still basing this on no forced entry, imo. The brother could have left that door unlocked without her knowledge after Ronald had left for work, imo.
I read about speculation of the the vcr/dvd player being too high etc., but if they think for a minute a kid can't scale a piece of furniture or find other ways to reach things...they haven't had climbers on a mission.
I see no reason why Teresa or others would not be allowed in the home right after LE arrived. It could be Teresa did give them the photo out of the frame inside the mh instead of bringing it with her as we earlier thought. They don't prevent other families from accessing their home when a child or an adult goes missing unless there are open signs of foul play, imo.