Using same data in different states of SMACH Concurrent-container

[ML-S]

Hey there,
I'm working on a project on which I have concurrent container in which two state machines run concurrently. The states inside those concurrently running state machines need to access and modify the same userdata. A more specific description with code can be found here:
Is there anyway I can use and modify a parent userdata in child-states?

[ML-S]

I found a workaround using mutable objects as userdata (see the answer to the stackoverflow-post I referred to in the issue description). Is there maybe a more elegant solution doing this using the userdata-structure?