What is the test for overturning a private agreement concerning child support?

[12] There is further dictum from Boca v. Mendel, at page 424 [R.F.L.], that I apply whenever there is consideration of the court’s setting aside of private agreements concerning child support: . . . parents should be free to negotiate and arrange their own affairs: see Pelech v. Pelech, 1987 CanLII 57 (SCC), [1987] 1 S.C.R. 801, 7 R.F.L. (3d) 225, [1987] 4 W.W.R. 481, 14 B.C.L.R. (2d) 145, 17 C.P.C. (2d) 1, 38 D.L.R. (4th) 641, 76 N.R. 81, per Wilson J. at p. 269. I do not think that child support is so very much different from other matters between separating parents including property and spousal support. Obviously, all of these things affect the standard of living of the child. Even with child support, the court should be reluctant to set aside the parents' own contracts or to interfere with their arrangements in the absence of compelling reasons to do so. It is public policy to protect a child from a weak parent's making a bad deal on the child's behalf. It is not public policy for the courts to get easily carried away with paternalism concerning the parents' own arrangements of their affairs. A balance between these considerations is needed.