I'm Lucy, and I'd be happy to answer your questions today.
You have the ability to file a Motion to Dismiss based on improper service. However, since you have actual knowledge of the motion, if you simply ignore it and do not attend the hearing, that's going to cause problems. When you don't appear, the judge is likely going to rule against you in your absence. To get the order removed, you have to file a motion stating that you did not receive notice of the hearing - and you can't do that, because you know about it.
If the judge does dismiss the motion because service was improper, then your ex-husband is allowed to refile, serve you properly, and request another hearing. Note that you're allowed to file a Motion for Contempt of Court since he's not paying and ask the clerk to schedule the hearing at the same time. So that might be another option to consider.
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