Rights to the inheritance of a person who died, with or without a will, before the effectivity of this Code, shall be governed by the Civil Code of 1889, by other previous laws, and by the Rules of Court. The inheritance of those who, with or without a will, die after the beginning of the effectivity of this Code, shall be adjudicated and distributed in accordance with this new body of laws and by the Rules of Court; but the testamentary provisions shall be carried out insofar as they may be permitted by this Code. Therefore, legitimes, betterments, legacies and bequests shall be respected; however, their amount shall be reduced if in no other manner can every compulsory heir be given his full share according to this Code. (Rule 12a)