99. The holder of a real estate broker’s or agent’s certificate shall use the mandatory form entitled “Amendments and Notice of Fulfilment of Conditions” where the parties wish to amend a mandatory form entitled “Exclusive Brokerage Contract — Sale of a Chiefly Residential Immovable”, “Non-Exclusive Brokerage Contract — Sale of a Chiefly Residential Immovable” or “Promise to Purchase” that they have already signed.