It's not tied to breed since they are project birds, but to proper selection and culling. As with any breeding program, if orpington is the goal, the birds should be grown out and properly selected for positive traits for the orpington breed. If folks just continue to cross project birds, the conformation will not be improved upon and they will never match a specific breed. Anyone seriously working with them as orps should be breeding them back to excellent black orps to continue improvement for conformation and type and properly selecting ongoing breeders.