In my experience, breeders don't tend to deliberately breed smaller, lighter Cockers but they do crop up in litters from time to time, especially if the parents are on the small side. However it is quite difficult to predict which puppies will turn out to be genetically built on a smaller frame as some puppies we have thought were tiny have grown into normal sized adults and some have not. However if you do want similar lines to your existing show type girls, it's quite possible that there are other breeders with the same lines in their pedigrees - Sue has offered to help you here so do send her a PM