In spanish, the names bf countries are not capitalized.

In the culture of most Spanish-speaking countries and Spain, women legally retain their two maiden surnames when they get married.

However, for social purposes (legally, she continues to use her original name in most of these countries), the woman can "eliminate" her maternal surname and add her husband's surname to her paternal surname using the preposition de. This in turn comes from the abbreviation of the Spanish tradition of calling a married woman "Señora de the husband's surname", where "Señora de" (Mistress) in this context means "Lady of" or "owner of".

It should be noted that this custom has been left in recent years because it is considered archaic, due to the movements of social equality between men and women that have developed in many of these countries.  

Well, this Western tradition in fact comes from the Middle Ages, in which a woman inherited her father's surname and changed it to match that of her husband's (who also inherited that of his father).

Following in the context of surnames in Spanish-speaking countries, the children of a couple will have the first surnames of each parent. The first surname being the paternal and the second the maternal.

For example, a boy named Miguel, whose mother is called María Luisa Duarte Márquez and whose father is called Luis Fernando Álvarez Hermoso; will legally have the name of Miguel Álvarez Duarte.

It should be noted that there are variations of this custom, as is the case of those born in Catalonia (Spain) where "y" (and) is added between the two surnames as :

Miguel Álvarez y Duarte

(Miguel Álvarez and Duarte)

So, in this case the name María Antonia Abad Fernández, Abad is the first surname, hence her paternal surname

.

As explained in the first answer; although a woman legally retain her Maiden surnames, she has the option to take her husband’s surname for social purposes.

Nevertheless, remember this custom has been decaying and a growing number of married women in Spanish-speaking countries are keeping both of their maiden surnames.

Now, in the case of the name Lourdes Blanco Cabrera, if she marries to Carlos Arias Delgado, she could present herself as (remembering the usage of the Spanish preposition “de”) Lourdes Blanco de Arias.  

Remembering the special case of surnames with the preposition y, this is one of those:

Luis Felipe González y Pérez

This whole name keeps the same rules, the first surname being the paternal and the second the maternal.

So, in this case, Pérez is the second surname, hence Luis's maternal surname.

Queen Sofia of Spain (formerly Sofia of Greece and Denmark) obtained her title of queen by marrying King Juan Carlos I of Spain. With this marriage she became the queen consort and had to resign from the Greek Orthodox Church and therefore her rights to the Greek throne (from her country of origin) and convert to Roman Catholicism (religion accepted by the Spanish monarchy).

She had this condition of queen until the year 2014, when King Juan Carlos abdicated the throne and was succeeded by his son Felipe VI. However, Sofía retains her noble title for life, being called Queen Mother and exercising protocolary functions as a member of the royal spanish family.

Letizia Ortiz Rocasolano is the secular name of the current queen consort of Spain. Title obtained by her marriage with King Felipe VI, who at that time was the Prince of Asturias.

It should be noted that Queen Letizia does not come from a noble family, in fact, she was a journalist before marrying Felipe VI. In addition, she had the title of Princess of Asturias until 2014, when King Juan Carlos I abdicated the Spanish throne by his son Felipe.

The number of Spanish households made up of one person or couples with only one child (or even without children) is increasingly growing, in contrast to households in Mexico and several countries in Latin America.

This is due to the change in the way of thinking with respect to what is a conventional home in recent years, not only in Europe, but also in other countries of the world and it is a movement of thought that is gradually coming to the countries of Latin America.

The reason?

The high costs of life, which makes expensive raising a child, in addition to the growing awareness in sexual education and contraceptive methods in young people.

Therefore:

The average family size in Spain is smaller than the average family size in Mexico.