Setting a default value will have that effect, in an XaaS blueprint, at least. I populate a drop-down list with an Orchestrator action, and then also set the default with (theSameOrchestratorAction) in the presentation. I guess you could do something similar setting visible to (action).length > 0, or something like that. Are you talking about a converged blueprint or an XaaS blueprint?
converged blueprint. using property definition with external action.