All legacies that lapse, and are not disposed of under the preceding Articles, accrete ratably to the universal legatees.
When a general legacy is phrased as a residue or balance of the estate without specifying that the residue or balance is the remaining fraction or a certain portion of the estate after the other general legacies, even though that is its effect, it shall be treated as a universal legacy for purposes of accretion under this Article.
La. C.C. § 1595