If I remember correctly, the only way the standard/ formal adverserial hearing ( Petitioner/ Plaintiff- Respondent/ Defendant) can be overcome for any modification to the original custody agreement, is in the event of an emergency where the moving party can demonstrate to the presiding judge/ surrogate assigned, the childs life or welfare is in actual danger. However, this would obviously only occur in extreme cases, and then only with some showing of actual or imminent actual harm to the child. It seems this isn't the case in your situation.
One thing is certain though, a modification to alimony/ child support is almost never even explored by the court unless circumstances have changed substantially- ie the parent paying support lost his job, the custodial parent recieving the child support remmaries, etc. In California, this is especially true. The state guidelines pretty much act as a floor for child support, but sleazy divorce lawyers and overly sympathetic judges can turn the guidlines into rubble relatively easily.
