Vt. 351, 353-54, 779 A.2d 42, 45 (2001) (declining to reach question of whether there was an actual change in circumstances when child support order previously agreed to by the parties was more than a ten-percent deviation from the guidelines). ¶ 7. The family court suggested that our current interpretation of § 660(b) creates a potential for abuse: noncustodial parents could agree to pay child support which exceeds the guidelines one day only to return to court the next with a motion to modify based on the percent age difference between the stipulated amount and the guideline calculation. Courts in some other jurisdictions have interpreted rules similar to § 660(b) in a manner that attempts to avoid this potential evil. See, e.g., Flannery v. Flannery, 950 P.2d 126, 132 (Alaska 1997) (<HOLDING>). In arriving at our interpretation, we found
holding that a rule presuming a change of circumstances when the amount of child support ordered deviates more than fifteen percent from what would be owed under a current application of the guidelines does not apply if obligor agreed to the deviation holding that the application of the guidelines in effect at sentencing rather than at the time of defendants conduct does not violate the ex post facto clause even if the current guidelines suggest a harsher sentence because the guidelines are only advisory not binding holding trial court may consider social security disability dependency benefits received by the child and may deviate from the application of the child support guidelines if application of the guidelines is unjust or inappropriate holding that the testimony of an obligor as to amount of payments was sufficient evidence to support findings of actual support paid recognizing impact of child support guidelines