Open APIs

Hello,
We're having internal debates about TMF645 "Check Service", for which i would appreciate the feedback of the community ;-)

1) When Services are evaluated, should these Services be (pre-) instantiated ? To be more concrete, should the Services be created in State "feasibilityChecked", "Designed" or potentially "Reserved" ?
2) If the Services are not instantiated, how can the Service Order (normally following the Feasibility Check) make reference to a previous Feasibility Check$
3) if the Services are (pre-) instantiated:
- How does the community sees multiple iterations of the Feasibility Check ? Typically in a cycle where a customer asks for a 1st evaluation of a set of Services, and then asks for an another evaluation of another set of Services (e.g. because the price to pay for the first set of Services is too high)
- Should the different rounds of Feasibility Check be executed based on "deltas" (a subsequent feasibility check is a delta compared to a previous one) or "from scratch" (ignore the previous feasibility checks)
- How can the "state" be cleaned up between the different rounds
- How can the state be cleaned up if a Service Order never comes ? I would in particular assume the result of a certain Feasibility Check to be valid for a limited period of time, especially if Resources are identified and reserved ?
- Should a Feasibility Check actually reserve/block resources ? 

Thanks !