Several thoughts here...
1. It doesn't sound like we know her full story with the prior family. There is definitely a possibility that she was mistreated there and now has trust issues with humans and what they can do to her with their hands.
2. I really doubt that there is any benefit to Coco to "socialize with the other cats" in a strange house, with other strange people, and unfamiliar smells. Why put her through that? I would say that most cats are not going to be too thrilled to be taken from their home and to a house with other adult cats in it. That's a tough thing, and doubly tough when it's a cat the sounds like she may need to be in a nice, safe, quiet home with people that she trusts for awhile.
3. You have cats, and it sounds like they are pretty mellow, and social, and older, and have acclimated to your home. She has not. I think reading her body language is paramount, and respecting her space and wishes. Don't try to treat her like you would your own cats. If she has had reason to be fearful of people's hands, then probably the worst thing you can do is "go in for a pet" in a fearful way, and targeting her back. Forehead, cheeks, and nose are far less stimulating and more "safe". Also, if you go in fearful, expecting an attack, an attack is probably what you're going to get (self-fulfilling prophecy) because cats are predators and they read fear, and when they see it, they'll happily treat you like prey. The "prey" dynamic with cats is actually a really weird and non-intuitive thing.
4. If you find that you have to "muscle" a cat into doing something, like you were saying "wrestle" her into a carrier, then you can be sure that the next time you have to do it she'll fight harder and resent it more, same with the next, and the next, and pretty soon you have a completely out of control cat who will fight viciously when confronted with that situation. If your response is violence, and overpowering the cat, and a show of strength, then that's what you are going to get coming back at you. So don't keep putting yourself, and her, into that situation! Next time try a toy, or a treat, of her dinner to get her to choose to go into the carrier. And if none of those are working, just stop putting her into that situation until you've built up WAY more trust capital with her. One hint: one of the best ways to build trust capital is to play with a bengal. But building trust can take a long time, especially for a cat like her.
Bottom line: I don't think she's a cat that you can take around to other people's homes with other cats there. You're setting her up to see her at her absolute worst in that situation. It would be a really special cat that would thrive in that sort of situation. She's not that cat.
The little monsters 3