We have decided to keep both cats. They are getting along much better now, though they still annoy one another sometimes.
Tiamat has learned that she can scratch the children and my son is enamored of playing roughly with her. We've had to set up a system of negative consequences for him having new scratches on his face, arms and/or hands. It seems to be helping, but both big kids still want to pick her up constantly. She is a remarkably patient cat and we are lucky to have her. She has her annoying habits, though. She is a licker and a meower. I've never heard such a loud cat that wasn't part Siamese. I suppose, since she seems to be a total mutt, that she could BE part Siamese, but if so it certainly isn't something one can see by looking at her. She's a calico (who looks like a tortoiseshell, as the white is confined to two spots) with yellow eyes.
Sozo got really loud for a while there, but it turned out that she was in heat. We got her spayed so that won't happen again, thank goodness. A Tonkinese in heat is LOUD. Sozo still spends just about all of her time in the bathroom in the little "cat condo" I bought for her. She's quite the anti-social animal, even taking into consideration that she is a cat, but she will put up with me extracting her from her condo at night after the kids go to bed. I put her in my lap and pet her while I sit at the computer. She allows this for a while, then retreats back to her condo. Hey, at least she's happy.