Does this mean he is in default and how do I obtain that status against him in court?

No, he wouldn't be in default but would be in violation of the Court's instructions. It is very possible that the Court will not accept an Amended Petition if now filed. However, family law judges try to be as flexible as possible especially when the parties are not represented by counsel.

I agree, he is not in default but it will likely make it very difficult for him to convince the Court to allow him to file an Amended Petition, unless he can show good cause as to why he did not file within the allotted time period.

I agree with my colleagues. Good luck to you.