I don't know if they have it in Canada, but here in America(and I'm sure you can buy it over the internet) we have a cat litter called "cat attract" cat litter. It's supposed to have some type of herbal additive that attracts cats to it. I read the reviews for it on Petsmart and 1 person said they had a 3 week old cat they had rescued and as soon as they put the litter in the box the kitten went straight for it! WOW! Impressive!
I used to work at Petsmart and ALOT of people bought that stuff and I only heard good things. Also, it's made with natural ingredients and is supposed to be safe for cats of all ages.(that includes kittens. Duh! LOL!)
Anyways, I think you should give it a try. I just looked at www.Petsmart.com
and they will ship to Canada(if you can't buy it there). You can check out the reviews on there if you want, there are alot.
Oh yeah, also, the litter comes with an unconditional guarantee!
Good luck with those 10 kittens!