Here's one suggestion:

Matrimonial regimes, or marital property systems, are systems of property ownership between spouses providing for the creation or absence of a marital estate, and if created, what properties are included in that estate, how and by whom it is managed, and how it will be divided and inherited at the end of the marriage. Matrimonial regimes are applied either by operation of law or by way of prenuptial agreement in civil-law countries, and depend on the lex domicilii of the spouses at the time of or immediately following the wedding. (See e.g. Quebec Civil Code and French Civil Code, arts. 431-492.). In Common law countries, the default and only matrimonial regime is separation of property, though some U.S. states, known as community property states, are an exception.

https://en.wikipedia.org/wiki/Matrimonial_regime

http://www.proz.com/kudoz/english_to_spanish/law_contracts/1...

Separate Property Definition:
A marital property regime wherein property acquired or owned by a married person and which, notwithstanding the marriage or, where recognized, a marriage-like relationship, remains the separate property of the spouse who acquired or to whom was gifted the item of property.

http://www.duhaime.org/LegalDictionary/S/SeparateProperty.as...

3.1. Which provisions can be modified by a contract and which cannot? Which matrimonial property regimes may be chosen?

The spouses have the possibility of choosing a matrimonial property regime via a marriage contract. As alternative forms of matrimonial property regime, Belgian law provides the separation of property and the universal community of property. In addition, the spouses dispose of the possibility of regulating their matrimonial property at their discretion, in so far as they do not stipulate anything that conflicts with public order or good morals (Art. 1387 CC).

http://www.coupleseurope.eu/en/belgium/topics/3-how-can-the-...

As to contrayentes, depends on the very type of document and whether the marriage has taken place or not.

That's my take; it's a cover-all- eventualities term.