Final answer:
The Licensee Buy Out Addendum is valid when the buyer (licensee) and the supervising broker both sign the form, ensuring the endorsement from the involved licensee and oversight by the broker.
Step-by-step explanation:
The Licensee Buy Out Addendum to the Contract to Buy and Sell is valid only if both the buyer (licensee) personally signs the form, and the supervising broker signs the form. These signatures are essential to legitimize the Addendum as a binding part of the Contract to Buy and Sell real estate. The buyer, being a licensee, has an interest in the transaction that must be acknowledged by their signature.
Furthermore, the supervision of the broker ensures that professional standards are met and that the buyer's interest is managed properly within the transaction. While it is customary for the principal broker to be aware of and often approve transactions, it is not specified that their signature alone renders the Addendum valid.