Here we go again/Intrastate Issue

Try to make long story short. Went through horrific custody battle over two and a half years ago with ex husband. I had just moved to Texas from Florida, and he lived in Georgia. Our original divorce decree with child custody and support was issued in Georgia. He filed in Florida claiming the Uniform Child Custody Jurisdiction Act. I won at a trial against is false allegations of child abuse (he was seeking change of custody) and the judge at the same time refigured the child support and entered a judgment on the Modification of Amended Final Judgment of the Georgia decree making it a Florida decree. Since the Judgment, I moved back to Florida (job transfered me) and then I have taken a better job in the north and have lived in Pennsylvania since Feb of 2001 and he has moved to North Carolina. He now as filed for a modification of the child support claiming decrease in his income. He has filed in Florida. I want to argue that Florida no longer has continuing exclusive jurisdiction since the child's home state is now clearly PA. But I have never registered the Florida order in PA. Will not registering the Fl order in Pa prevent me from getting the case dismissed in Fl over the jurisdiction issue? Or is it clear that he needs to file in PA and start all over? I have 20 days from yesterday to answer his suit.