Currently it is not clear which Task Plan(s) should be considered 'top_level_plans', or which ones would start automatically active, i.e. with any Tasks in the 'available' state.
Some Task Plans within a WP are hand-offs from an initial Task Plan (e.g. clinic reception), and presumably should not be by default active when the WP starts execution.
We need a definition of which Task Plans are considered 'entry points' for execution. Commonly it may be only one, being where the subject first appears, but this is not guaranteed to always be the case.