Sounds like it's gone wonderfully, well done you .To be fair, he was already a very laid back cat, the intro happened accidentally, Boo and I were in the garden when my Cat came back... He wasnt sure at first but he came over to investigate and he only arched his back when boo approached him, she is respecting his body language well and stays back when he looks hacked off, we have the feliway plug and i think that has helped a lot, also when casper ( cat) came in the same room as us i was armed with tuna and sardines, which i fed them both together. I think it is more about the cat than anything else, but i have always allowed him to control the situation and that has worked very well
How are you teaching Boo to stay behind the line when you eat?!