I think this feature is too specialized. Would the ability to group stations into ‘parallel groups’ helps? Previously there have been proposals to create ‘sequential groups’ — stations that must be serialized can be put into the same group, and stations from different sequential groups are allowed to run at the same time. Your application would be the opposite of this — stations that should run at the same time can be put into the same ‘parallel group’, and stations from different parallel groups must be serialized.