[Storyteller.]

I'm sorry you haven't received a response to this yet! I was actually hoping that somebody who currently has rabbits would chime in to offer their experience, as my last pet rabbit was many years ago so I don't have much recent experience with them. That said, I did have rabbits growing up, and my dad used to keep them as well, so hopefully I can still help a bit.

There's definitely more than one way to introduce a new pet to an existing one, so even if most of what you've read online has said to put their cages together, that doesn't mean that's the only way to go about it. It sounds like they're interacting a bit, and they can see each other so they're both probably getting used to the presence of the other rabbit. If you haven't had any problems this far I'd say to stick with the approach you're going with - having one in a play pen while the other free roams. It might help to switch roles with them if you haven't already, so have Bella free roaming with Cashmere in the play pen and then change it later on so Cashmere is allowed to roam (assuming you're comfortable letting her have the run of the house) while Bella is in the play pen. That might help Cashmere feel a bit more confident, as she'll be allowed to approach Bella at her own pace and also to back off if she feels a bit more shy.

When they're both fine with that and you're happy with how they're acting around each other, you're probably okay to introduce them properly - but, of course, under close supervision. Slowly let them have more time around each other until you're sure that they're friends, and don't be scared to let them settle their differences. A large part of this process is letting the pets create their own boundaries and learn to respect each other's comfort zones, so the less human interference in these earlier stages the better.

Once again I'm sorry that you didn't receive a quicker response, but I hope this was at least somewhat helpful. I also hope that Bella and Cashmere do end up being friends, and please feel free to give us updates (particularly ones with pictures of the bunnies, I always love seeing pictures of people's pets and I'm sure I'm not the only one) on their progress!