http://www.gccfcats.org/registration.htmlhttp://www.gccfcats.org/ethics.htmlYou don't say what breed or registration body the Breeder registers with, but if your friend were to go ahead and collect the kitten, then having a contract typed up to the effect that the kitten (whatever name (pedigree details including colour - check GCCF site for the breed), sex and breed, age) collected early and the reason for this, followed by registration with XXX body to follow and the date, signed by both parties (and possibly a third person) might cover the situation.
Of course I could be completely wrong as I'm not a lawyer or legal person ;)
I'm surprised that this person has no-one who could help out in an emergency, membership of a breed club often means that in times of real need people rally round ;) what is going to happen to the mother of this cat? any other cats the breeder has? someone will have to look after them, so I can't really see why the kittens need to leave this early? I can't believe a caring breeder would EVER allow one of their kittens to leave unvaccinated, it's something I wouldn't risk personally :(
On the other hand it could just be a case of this person wanting rid of the kittens as they become really active and hard work, but are far too young to sell/vaccinate?
Registered kittens should have at least an enteritis inoculation and a full course of cat flu inoculations and be at least 13 weeks old before leaving the breeder.
Having bred pedigree Burmese myself (long ago now) I know just how much hard work they are once they really get going - mine used to swing from the curtain tops LOL
Suggest you check whether this breeder is at least a member of a breed club (and check with the club ;) )
ETA. I assume that if the full price has been paid for the kitten then vaccinations by 13 weeks should be included in the price. Collecting the kitten at 8 weeks and unvaccinated means that the new owner will be responsible for the cost of vaccs. Will there be any sort of refund to cover this?