A will or other instrument made under an order under section 19 is not valid unless the following requirements are satisfied—
(a) for a will—the will is executed under this part;
(b) for another instrument—the other instrument is executed in the way a will is required to be executed under this part;
(c) 1 of the witnesses attesting the will or other instrument is the registrar;
(d) the conditions of the order, if any, are complied with.
Note—For the holding of the will or other instrument by the registrar, see subdivision 4 .