Comments
Why can't EligibilityRequest be handled using Order? The data elements all map and Order is about managing workflow-type requests and responses. The only elements it's missing is the ruleset stuff. And Order at least mentions the patient (i.e. "hopefully" Covered party). The only question is what Order.detail should point to, which would logically be either the coverage (if you're asking "is the coverage in force) or the planned/proposed service

Grahame's Comments
whate service? What is this resource doing? Though I don't think that Order is what we're looking for. I think this pattern is all wrong; we need to look at this as a decision support thing