Can you breed a Yorkie Dam to it's Daddy's Mama's Daddy who is also the Daddy of the potential breeding Sire Yorkie?

Yes, you can breed a Yorkie dam to her sire's maternal grandfather, as this does not violate any breeding restrictions. This type of breeding is known as line breeding, which aims to reinforce desirable traits within the lineage. However, it's essential to consider the health and genetic implications of breeding closely related dogs, as it can increase the risk of inherited health issues. Always consult with a veterinarian or a professional breeder before proceeding.