After a lot of thought and Googling, boy kitten is now known as Benny. Rather like Benny in Topcat, he is devoted to Lola (Topcat) and will follow her into almost anything. I’m sure she will get him in trouble one of these days!
I’ve finally managed to get a reasonable photo of him.
Max is pretty much OK with them – he still hisses but it’s all mouth and no trousers. Minnie is taking a bit longer to come around and has taken to the top of the wall cupboards in the kitchen for some of the time.