Only one member of our family has not welcomed him into our home - our 12 year old female tortoiseshell, Katrina. Her nose is seriously out of joint. Lots of growling and hissing and yowling, and lots of time spent outside to escape the stress of having an intruder in her home. She is a very dominant, very territorial cat. She is also extremely sensitive and feels everything very passionately, and she doesn't let go of a bad mood easily. She was depressed for months after her closest friend, our Labrador cross, died several years ago. A few years later, our oldest cat (a very timid and submissive tom that she liked) died as well, and she's mostly been an only cat. We've introduced her to two separate young kittens, both of whom died at a couple years old (one most likely from a car, the other from FeLV). Both of them she rejected at first, but eventually warmed up to, shortly before they died. So there's a good chance she'll warm to Smudge.
And indeed, she's already gotten more tolerant of him. They can now be in the same room and aware of each other without hissing and growling from her, provided he keeps a good distance. Weirdly enough, she actually shows signs of being submissive to him, backing down when he came to beg for some of her wet cat food (we feed them mostly dry cat food, with wet being a treat). Maybe she lost her confidence because we babysat a coworker's dog for a week about a month ago - a basset hound who Katrina was terrified of.
It's funny -the turning point in their relationship seems to have been the first time she swatted him. I made the mistake of trying to distract her from a face-off by dangling string near her. It didn't distract her, but Smudge was enthralled, and finally he decided to just go for it, never mind the cat. She swatted him and he ran away in sheer terror. Now, he's a bit afraid of her (whereas before he was just curious, a dangerous thing to feel towards an unfriendly cat) and she seems much more tolerant of his presence.
Oh, and I've figured out a great game for playful kittens - get a ball of yarn, grab the end of the thread, and throw the ball on the floor near the kitten. Then use the end of the thread to reroll the yarn ball, letting the kitten play with the ball the whole time. It's very little effort for the human, but great fun for the kitten.