La. Stat. tit. 9 § 2011
A revocable trust instrument need not designate the beneficiaries upon the creation of the trust but may instead provide a method whereby they are determined at a later date, but no later than the date when the trust becomes irrevocable. A beneficiary thus determined may be a person who is not in being when the trust is created, as long as he is in being when the beneficiaries are determined. If beneficiaries are thus determined, any provision in this Code that refers to persons in existence at the creation of the trust shall be deemed to refer to persons in existence at the time when the beneficiaries are determined under the trust instrument. The interest of the beneficiary may be conditioned upon the beneficiary surviving the settlor for a period of time permitted by Civil Code Article 1521.
La. R.S. § 9:2011