I would be interested to know this too Saffron - it would be interesting to know what advice you had been given in the past too, in case this may be helpful or informative here.

I might give them a viking funeral (but without the longboat) and bury their ashes in my back garden, then plant some pretty flowers in my flower bed over them.

If the kittens were deformed (luckily not had one of these yet) or more than one dead kitten, I would not do the same mating again.