When a decedent dies testate and his testament designates an executor, but his testament does not provide for independent administration of the estate as provided in this Chapter, all of the general or universal legatees of the decedent may agree to have an independent administration and in the application for filing for probate of the decedent's testament, or thereafter, collectively designate the person named in the testament to serve as independent executor. In such case, the court shall enter an order granting independent administration and appointing the person designated in the application as independent executor.
La. C.P. § 3396.3