What is the test for establishing that there is sufficient corroboration for a claim of false imprisonment?

In Koop v. Smith (1915), 1915 CanLII 26 (SCC), 51 S.C.R. 554, Duff J. said: … when suspicion touching the reality or the bona fides of a transaction between near relatives arises from the circumstances in which the transaction took place then the fact of the relationship itself is sufficient to put the burden of explanation upon the parties interested and that, in such a case, the testimony of the parties must be scrutinized with care and suspicion; and it is very seldom that such evidence can safely be acted upon as in itself sufficient. [at 558] and I think the true rule is that suspicious circumstances coupled with relationship make a case of res ipsa loquitur which the tribunal of fact may and will generally treat as a sufficient prima facie case, but that it is not strictly in law bound to do so; and that the question of the necessity of corroboration is strictly a question of fact. [at 559]