A gift by marriage contract in favour of the spouses and the unborn children of their marriage may still be made, on condition of paying indiscriminately all the debts and charges of the donor’s estate, or under other conditions the performance of which would depend on his will, by whomever the gift is made : the donee will be bound to fulfil these conditions, if he does not prefer to renounce the donation; and in the event that the donor, by marriage contract, has reserved to himself the freedom to dispose of an instrument included in the donation of his present property, or of a fixed sum to be taken from that same property, the instrument or the sum, if he dies without having disposed of it, will be deemed to be included in the donation and will belong to the donee or to his heirs.