Art. 823. The father or the mother may dispose of one of the two-thirds destined as the legal portion in favor of one or more of their children or descendants.

This portion is called a betterment (mejora).

Art. 824. No other incumbrances can be imposed upon the betterment than those which may be established in favor of the heirs by force of law or their descendants.

Art. 825. No gift by contract inter vivos, either simple or for a valuable consideration, in favor of children or descendants who may be heirs by force of law shall be considered as a betterment if the donor has not expressly declared his intention to that effect.

Art. 826. The promise to give or not to give a betterment made in a public instrument of a marriage agreement shall be valid.

Any provision of the testator in contravention of the promise shall not have any effect.

Art. 827. The betterment, even if made with the delivery of the property, shall be revokable, unless it has been made in a marriage agreement or by a contract involving a valuable consideration made with a third person.

Art. 828. A bequest or legacy made by the testator to one of his children or descendants shall not be considered as a betterment, except when the testator has expressly declared such to be his intention or when it can not be included in the portion he can freely dispose of.