What is the test for establishing that a person is mentally competent to produce evidence in a family law proceeding?

As the equivalent rule has been most commonly interpreted in other provinces, it is to be used only to assist the court in interpreting evidence and not to create evidence in order to prove a fact in issue. Consider for example, the decision in Drury v. Wiwchar, [1984] W.D.F.L. 046 (O.H.C.). The issue before the court is summarized in the headnote: In a proceeding under the Ontario Family Law Reform Act, the respondent sought an order for partition and sale of the jointly held matrimonial home, proposing to purchase the applicant's one‑half share at fair market value. The applicant, who was resident in a nursing home, had consented to the order. However, the respondent was concerned that the applicant might be mentally incompetent and that the order might therefore fall under attack in the future. Accordingly, he sought a second order directing psychiatric assessment of the applicant regarding her mental competency, a trial of the issue, and an order declaring the applicant mentally incompetent and appointing the official guardian as her next friend and guardian in the proceedings.