Young cats can be a lot of fun, but be careful. Older cats tend to be more sluggish and like to sleep a lot, whereas kittens tend to like to play. If you mix the two, you could end up with some unhappy kitties. My cat was 17 when he passed away (had him since I was 5) I waited a year and got another, and then recently got another kitten. Even though Ruf is only 2 1/2 yrs, Freckles is a handful for him! He often gets annoyed that she likes to play with his tail and wrestle all of the time. So with cats that are 16 and plenty set in their ways, not to mention may have aches and pains, it may be too much for them to have to put up with cats that will be much more active.