Not sure if you were refering to me specifically, but after we talk to the vet today, we may see if the younger, injured one will stand up for himself. We bought the Feliway and plugged it in. So far they can't stand each other.
We had a situation with the younger of our two kittens a couple of years ago. They are seven months difference in age. We switched to fragrence free litter (arm & hammer) and locked him in a room when unsupervised. We didn't let him out until he used the box and only for short times, one hour or...
How has this turned out. I noticed your post was from a few months ago. Our cats started this behavior yesterday. It started when there was another cat outside on my deck. One of my cats is hurt and we're taking them to the Vet tommorrow.