Wow, thank you for the quick responses ladies.

I know I haven't given it ANY time yet. But I just hate seeing her this way. I asked Bruce if he thought she'd ever calm down and he said yes. So that made me feel better.
I will do the thing with exchanging their scents. Actually, Jax doesn't have a problem. I was holding him and Paizly was hissing at him and he only fluffed up his tail, he never hissed or growled back.
It will be hard to do the carrier in the room and Paizly to see/sniff around it. She'll just run off and go under the bed, chair or in the closet away from it. But I'll give it a try later in the week.
I do have feliway spray. I could try spraying that on her collar. Thanks for the idea Tracey.

I love hearing success stories on this subject. Mac and Ming's story really gives me hope. Since I've sorta been through this once with Taz (age 13) and Paizly (age 2 months). But Taz tolerated her. He'd hiss or growl a teeny bit, but nothing like Paizly is doing with Jax.

I know I need to just have patience and relax. And I will work on that.

Oh, I almost forgot one question, again. When she is hissing and growling at him what do we do? Do we just ignore it and let it happen, or do we talk soothingly to her to try to help her calm down? It's hard to sit there and watch her throw a hissy fit, but I have been doing a bit of both. Ignoring it and talking calmly to her.