We introduced them to Mutz and Mako and it went just fine. Honestly, I've never seen such a smooth and easy cat addition in my life - and neither has Chris. Mako was a little nervous (okay, let's be honest - he was terrified of them) at first, but he's quickly warming up. Mutz could literally not care less about them. Here's the video I took of their introduction to him.
As you can see, he was completely unimpressed with all of their hissing and arching. He wanted nothing more than to sniff them. Now that he's satisfied, he hasn't given them much notice at all. He minds his business and they mind theirs.
I just want to make it abundantly that these kittens in no way serve as a replacement for Morgaine. No-one will ever replace her. But Mako needed a playmate and these kittens sort of fell into our laps in a very bizarre and convoluted chain of events. Who am I to argue with fate?