The WBFSH ruling states that:

• If the breeder who made the choice of the genetic match still owns the foal at birth, they will be registered as the breeder.
• If the breeder has sold the mare in foal, or the embryo before birth, and wants to be registered as the breeder, they must make an agreement with the new owner, who will birth the foal and notify the studbook for its registration.

Additionally, ACE Group Inc. has established the rule that:

• The foal, once born, is fully entitled to have a name and prefix chosen by the new owner, the breeder is still the Person/Stud who decided the match between stallion and mare, unless there is a prior agreement or contract made at the time of sale of the pregnant mare.
• The term “pregnant mare” also applies to a recipient mare in the case of embryo transfer.
• ACE Group Inc. strongly recommends that a contract be in place at the time of sale of a horse, recipient mare, or embryo. If no contract exists, these rules will apply.