Is there any case law or case law that would require the court to conduct a minute analysis of a joint bank account?

First, it should not be the task of the court to conduct a minute analysis of an account that in reality served as the family's joint bank account. Good reasons for avoiding such a process, albeit in the context of a marriage, were summarized by McLachlin J. (as she then was) in Moge v. Moge, 1992 CanLII 25 (SCC), [1992] 3 S.C.R. 813 at para. 116, 43 R.F.L. (3d) 345, (discussing economic hardship resulting from marriage): This leaves the question of evidence. I agree with my colleague that evidence of the spouses' respective contributions and gains from the marriage is necessary under s. 17(7)(a). I do not think the evidence need be detailed, in the sense of a year-by-year chronology of sacrifices and gains. This is not an exercise in accounting, requiring an exact tally of debits and credits for each day of the marriage. It is beyond the means of most parties and our overburdened justice system to devote weeks of lawyers' and experts' time to providing such a tally. Nor do I think it necessary. It is clear that certain things must be done to maintain a family. Income must be earned. Food must be bought and prepared. Children must be cared for. And so on. …