Leela I feel for you! I have a 2 year old Cat who broke her leg when she was only a kitten and I had only had her for a couple of weeks, but she is my baby and she comes home the same times every day so if she is a bit late I panic!! She went missing for a weekend a while back and it was horrible!! The other kitten will get use to not having Ronnie around, and as they were brothers it may not be good to replace the kitten with another one just yet, if it is male kitten you get they may fight, and if it is a female kitten you get, well obviously you dont want lots of kittens!!