the entire estate should go to Mrs. Opp as long as she lived, and that after her death a $50,000 life insurance policy should be purchased for the son and the remainder of the estate should go to the son's four children, a boy and three girls. In connection with that will, Mrs. Opp signed a waiver similar to the one here involved.
 Mr. Opp later told his attorney that he had found that his grandson had no more regard for the value of money than his own son had, that he had already given his son a *481 fortune, that he wanted to treat the son and the grandson alike and provide an annuity for each, and that he wanted to change his will accordingly.
 On October6, 1938, the will here in question was executed. This will gave $2,500 to an old employee, provided he survived the testator, and gave all of his personal effects, his interest in the household furniture and any automobile he might own to his wife. The will then gave "the entire rest, residue and remainder of my estate, of whatsoever kind and character and wheresoever situated, which I may own or in which I may have an interest at the time of my death," in trust to Louis Almgren and Frank A. Frye, who were also named as executors. The trustees were directed to pay all of the net income from the trust estate to Mrs. Opp as long as she lived. It was then provided that upon the