Can retroactivity be ordered back before the application date?

Therefore, I am satisfied that I have jurisdiction to vary the original order, that there is a change of circumstances and the question remains whether retroactivity going back before the application date can be ordered. Considering the case of Razutis v. Garrett, (supra), is “the evidence sufficiently persuasive to justify a variation that will deprive the parent who has carried the burden of the care of the children of any hope of collecting what both parents agreed was reasonable support in the circumstances as they existed when the consent order was made”? I do not believe the fact that this was not a consent order makes a difference.