between a Yorkie or a Westie.  I have 2 x CKCS and children aged 6 and 13.

Advice needed please!!

Im biased, a westie, they do get on well with cavies, my sons girlfriend has cavies, they also get on well with older children when properly trained.  I find yorkies smaller and can get under your feet more to trip you up. LOL!!!!

I'm biaised too, get another Cav, they're the best dogs!!

that is true about yorkies getting under your feet and tripping you up it has happened to me .when i first bring them home as puppies i walk about with no shoes on.
3 of mine would be ok with children, but one would not or he might come round if he thinks he getting a bit of food,