You can certainly file to a name change. You will need to serve the other parent and if they do not respond it would be granted. If they object...

You should talk to an attorney offline via a consult to learn what rights and options you have................................

It would be smart to be represented, especially if you were not successful on appeal, and/or if the other side is represented.

Draft a written agreement with the terms you two agree to. You may want to hire an attorney to do that.

You can certainly try to argue it. It would be your burden to prove and prove what he really should be earning.

You should file a request for default.........Good...

No, not necessarily. You still need to prove your case. However, it does make it easier to be successful .

You will need to file a petition for contempt with the court first and the court should be able to assist you on that.

File what is called exceptions: https://www.calvertcountymd.gov/DocumentCenter/View/40632/Exceptions-Form-PDF good luck.

You should have the kids talk to their dad. If he still wants them to go and they decide they do not want to, he could file contempt against you,...