Concurrent smach state where if one side finishes the other must stop and finish aswell

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I'm implementing a state machine using smach, and my point in this particular part is to have a state that is continuously checking if my UAV can visualize the marker by implementing a MonitorState, and another concurrent state that is meant to draw the UAV towards that marker. However, if it cannot detect the marker, the Monitor State finished, but it gets stuck waiting for the other state to end. Is there any way that when the MonitorState ends, the concurrent state ends aswell? I was thinking Petri Net wise, as in, when the transition is triggered, they must both transition.