What most naturally follows?

How to move to another state when you have custody of your child
Identify if you have sole custody.
In some-but not all-states, you can move your children out of state if you have a permanent order for sole custody. This is the law in california, for example.
However, many states don't acknowledge the concept of " sole " custody, and their laws will be very different. Accordingly, you always need to find out your state's requirements.