Article 1033
Every person who is in relation by blood to any degree and in any lineage with another person will have the same relation by blood in the same degree and lineage with the husband or wife of that person as the case may be . The father - in - law and the mother - in - law of a man therefore, constitute his relations of the first degree and the brother and the sister of the husband of a woman constitute her relations by marriage of the second degree.