691. Benefits under a retirement plan contemplated in article 415 or under a contract of insurance of persons, where these benefits would have been part of the succession or would have been paid to the creditor had it not been for the designation of a subrogated holder or a beneficiary, by the deceased, during the three years preceding the death, are classed as liberalities. Notwithstanding any provision to the contrary, rights conferred by benefits under any such plan or contract may be transferred or seized for the payment of support due under this chapter.