Father Filed Complaint for Declaratory Relief from Legal Determination of Paternity

[DreaRenee]

My question involves paternity law for the State of:OREGON
My ex's first attempt at contesting child support on the basis of not being bio dad, of our oldest, failed on the grounds that he signed AOP for both our sons over 6 years ago, he is on their birth certificates, & they have his last name.
To be fair, there was a good chance my ex was not bio dad. But we both decided shortly after the birth of our 17 year old that DNA testing wasn't needed, they were father & son & nothing would change that.
Yesterday I was served a summons. The father of my kids has hired a lawyer and filed a CLAIM FOR DECLARATORY JUDGMENT against me. It is a complaint for declaratory relief filed in accordance with ORS 28.010 et seq. He is asking for a judgment declaring he is not the legal father of our 17 year old son on the basis that he is not the biological father.
I can't find a single law that supports his lawsuit, but I must be missing something, otherwise why would his lawyer file the complaint. The previous advice I received was incredibly helpful and I am hoping for more of the same.
The thought of this man asking to no longer be the father of my son, my heart hurts so badly for him. It is getting very difficult to hide all of this from my boys, & the stress is wearing on me. Help please...

[Mr. Knowitall]

Didn't we already go over this?

[DreaRenee]

Sorry for the confusion, I left out some needed information. My questions back in March were pertaining to an Administrative telephone hearing that the father had requested in order to challenge the proposed monthly support amount. In the final order the judge actually raised the child support amount, added in medical support, increased the lump sum of past support owed, & ruled that my ex is the legal father of both our boys.
In the final support order it states under the provisions of ORS 416.427(6), you may appeal by filing a petition for review in circuit court of the county in which the order was entered, & within 60 days of the date the order was was entered. Once the petition for review is filed the circuit court conducts a hearing de novo. But the final order was not appealed in this manner. Instead my ex filed a complaint against me, in a different county, & well after the 60 days. I am now the defendant in a trial that will have a jury. I do not understand the statute under which the complaint is filed under. But because the appeals process was not followed do I have grounds for a motion to dismiss?