Lawyers are not infallible, neither am I. But my interpretation of the law is that, as long as one of the parties in a custody case remains in the original jurisdiction, then that jurisdiction still applies. While it may be possible to transfer jurisdiction, a petition to do so has to be submitted to the court that has jurisdiction and is not automatic. If both parties have moved from the jurisdiction, then jurisdiction rests where the children live. A petition to change jurisdiction can then be filed with a court local to where the children reside.
I would suggest consulting Family Law specialists in both states. Many will offer free consults. Also some law schools will have clinics that may help you prepare the petition is you want to go pro se.
I do wish you luck. Our purpose here is to help you understand the law so you don't waste time with court motions that will be denied.
I hope you will keep us posted.