According to this forum discussion the Flow step types behave different compared to other step types, making customization hard:
http://forums.ni.com/t5/NI-TestStand/Where-does-logic-for-flow-control-step-types-live/td-p/2607349
Rectifying the behaviour of the Step types may be out of reach as this would dig too deep into architecture.
But there is a lack of documentation of the behaviour of these steps. E.g. just to mention the fact that step type functionality is in those cases tied to the step type name would help a lot.
