Do I have to?
The order states my ex shall claim the children as dependants.
The order is now past its 90 day review period.
The order does not state that I have to sign Form 8332.
Do I have to sign it without first being taken back to court?
Re: Do I have to? yes
An order stands until it is changed by the court.
I believe that you have to sign it. The order does not have to say you have the sign the indicated IRS form.
If there is review date, and you believe this is contestable, I suggest you get this back to court ASAP.
If you need any more assistance, contact me.