Hi Bran,
Just a quick check: Have you seen Christians vide that Ernesto refers to? I have feeling that we might have some misunderstanding related to this about when and how the redefining state machine is introduced and how much "manual" work it currently is.
I think the core question here is related to "when the modeler decides to modify the inherited state machine". In Christian's video this can be seen at the point when the user right clicks on the capsule and selects "New UML-RT Child > StateMachine" in the subclass, which then automatically creates the redefining statemachines, automatically establishes the redefinition relations, including applying the RTRedefinedElement stereotype and applicable elements.
As I indicated this in my response, we have had actually exactly the same discussion about when the user navigates into an inherited composite state by double-clicking on it, and either the user selects to navigate to the inherited diagram in the context of the superclass, or the user has the intention of modifying the "inside" of the composite state, and thus we redefine the composite state and create a "redefined" nested state-machine diagram for that composite state.
I think that we have something very similar here, i.e. either the user is happy with looking around in the inherited state-machine (in the context of the superclass), or the user has the intention as you say, to start modifying the inherited state-machine. The question is just how and when we are going to ask that question? For the composite state case, we have the double-click action on the a composite state. For the top level state-machine itself, we don't have anything similar.
So the question is if it is "good enough" to do exactly as Christian already have done and what is showed in the video, i.e. the user explicitly selects to create a state-machine in the subclass using "New UML-RT Child > StateMachine".
Or if we need to find some other "gesture" for the user to indicate that the intention is to start modifying the state-machine, similar to the case for inherited composite states.
/Peter Cigéhn