In social relationships, each spouse may, if the other agrees to it, to use the surnameof the later or to add italong with his own.

By agreement of the spouses each of them may add along with his surname the surname of the other. The addition is made by a joint statement before the registrar and is valid until revoked before the registrar by joint declaration of the spouses or by a unilateral declaration made by any of the spouses individually, which shall be notified to the other spouse. If the marriage is dissolved by divorce, the declaration shall be deemedas revoked. If the marriage is dissolved by death, the addition continues to be valid, unless the surviving spouse remarries or makes arevoke statement before the registrar.

Article 1400 – Contribution Claim in acquisitions

"If the marriage is dissolved or annulled and the property of one of the spouses,since the contracting of marriage, has increased, the other spouse, provided he contributed  in any matter to such increase, will be entitled to claim the attribution of that part of the increase which is due to his contribution. It will be presumed that such contribution amounts to one third of the increase, unless a greater or lesser contribution or no contribution at all can be proven. The preceding paragraph shall apply mutatis mutandis in case where the separation of the spouses lasted formore than three years. In the increase of theproperty ofthe spouses, the property acquired by donation, bequestor inheritance or disposition of possessions from these causes is not been calculated».