I still think my two look like M and F so I decided to have another go after the failure noted in post #92. This time I modified a reptile carrier into an acclimation box. I left the box in the tank over a week. I fed the box first every day so the new guy would get food and it also worked out well getting him used to all the other fish at feeding time since they were trying to get to the food.
I ended up taking the lid off and setting the box on the rocks. The resident CBB swam in to the box and a few minutes later they both swam out.
It's only been 24 hours but I've seen zero aggresion towards the new guy and he is has no trouble competing for food. Fingers crossed it continues.