I want to edit a variable of the TestButton blueprint, in Editor. Specifically I want to assign each instance of TestButton a different ID, as it defines what the button does. How do I do this?
Create a variable for setting your ID(Name or String) in your master BP. In the BP containing the child components, use the components as variables, and call the ID variable to set it in the begin play or construction script depending on your needs.
You can also setup an interface but that is slightly more complex.