If I have a Texas child support order, but all parties and the child have moved to another state, what should happen to move the caseto the new state?

Since everybody is in the other state, maybe you domesticate the Texas order there, and file a motion to determine arrrearage, and determine that it is “x” or zero, whatever you can work out with the other parent. Then, the other state has jurisdiction, not Texas. Since I practice in the North Texas area, meaning Dallas and area counties, you should contact an attorney in your county. The best way to do that is to contact the local county bar association or the State Bar of your state and ask for a referral to a family law attorney.