What is the test for a variation in the terms of a spouse's marriage contract?

As Sopinka J. wrote in Willick v. Willick, supra at 21 that: ...the change must be a material change of circumstances. This means a change, such that, if known at the time, would likely have resulted in different terms. The corollary to this is that if the matter which is relied on as constituting a change was known at the relevant time it cannot be relied on as the basis for variation.