What is the test for overturning a finding that there was no undue influence or unfairness on the part of Respondent's wife?

There can be no doubt as to the confidential relationship existing between respondent and his wife, that the real property described in the deed was her separate property, and that there was no consideration for the deed here under attack. This would, under the authorities, cause a presumption to arise that the deed was the result of fraud and undue influence. Under such circumstances the following rule stated in Azevedo v. Leavitt, 76 Cal.App.2d 321, at page 324, 172 P.2d 704, 706, is applicable:

'The donee must rebut the presumption by evidence which is sufficient to overcome it, and whether the donee has overcome the presumption is a question exclusively for the trial court. Before an appellate tribunal would be justified in reversing the finding of the trial court that there was no unfairness, fraud, or undue influence on the part of the donee, it must appear that there is no substantial evidence to support such finding. As this court said in Laherty v. Connell, 64 Cal.App.2d 355, at page 357, 148 P.2d 895, at page 896: 'In order to prevail on this ground, the appellants must demonstrate that there is no material, credible evidence or no reasonable inference from the evidence to support the challenged findings.''