Does a Will need to be executed before or after the execution of the Will?

Doubt exists if there is sound modern authority for indulging in presumptions as to whether alterations on a will were made before or after its execution. Matter of Easton's Will, 84 Misc. 1, 145 N.Y.S. 373; Crossman v. Crossman, 95 N.Y. 145, 153; Matter of Ross' Will, 177 App.Div. 719, 721, 164 N.Y.S. 884, 885. In any event, it seems clear that the burden of establishing the time of an alteration rests upon him who benefits from the change. Matter of Ross' Will, Supra.