Are you sure? The rules only say you must not accept queens on the non-active register (for which indeed there are penalties), they don't say anything about unregistered cats, as far as I can see, except in rule 3g which specifically permits stud owners to accept queens that are not registered with the GCCF (the assumption of course will be that they are registered with TICA or FB but it doesn't actually say that). And of course non-pedigrees have been used in the development of some breeds, were all those registered first?

Having said that, the chances of the OP finding an owner of a registered stud prepared to do it are minimal - the rules may allow it but fellow breeders will certainly disapprove of anyone doing it.

Liz