Bringing Ti into, and Miley out of, the bedroom might be a start. I know Peanut is most comfortable with us when we are in bed, and that might just be a good bonding spot. (sounds kind of silly if you think about it ). You might try the bathroom thing, but I almost think you shouldn't force him into anything. If, like Luckies4me said, that they really bond with their humans, it could be that he's just really confused with the unfamiliar territory and unfamiliar with the hissing and growling that Miley is doing.

You have to do what your instincts tell you, but I think he's doing great, and playing with you - even if it is from under the bureau - is a good start, and the fact that he's eating and using the litter box as normal is another good sign that he's starting to feel more comfortable. I know he'll be out and about soon, and I agree that by the end of the weekend he'll definitely know this is his new home - and his new sister.

Please keep us updated, and pictures of paws would be wonderful. He certainly doesn't look like 17 lbs of cat, but he sure is beautiful.