Modification of a contract (subsequent to its formation), when the active or passive conduct of a party indicates an obvious and unequivocal intention to consent to the definitive modification of the contract, and not a simple punctual and temporary tolerance of a situation contrary to the letter of the contract. Since January 10, 2020, the tacit amendment of the by-laws of immovable is no longer possible, any amendment must be made expressly, in minutes or in a written resolution of the co-owners.