Legal Question in Family Law in California

Amend the motion and make sure the other party is properly served 16 court days before the hearing - add five calendar days if by mail. You can also try filing a supplemental declaration or bring it up in your reply to the other party's Response. Courts sometimes allow this, but will depend on whether you are making a new request of the court or just giving more reasons why your original request should be granted.

You can file supplemental declarations, but judges frown on it and for a good reason. It is unfair to your opponent to be given notice of an OSC or motion, begin preparing an opposition, and then be bombarded at the last minute with "oh by the ways."