:    This response is based on the information provided.  We suggest you discuss with your contracting team, program manager and/or legal department as appropriate. 

We assume you had the appropriate clauses in your contract with the prime and required it to flow those clauses down to its subs.  We consider it reasonable to interpret the contractor met the intent for competition by inviting six offerors.  From this offer, does the prime believe it can determine a fair and reasonable price was offered?  It is the prime's responsibility to determine fair and reasonable in this situation, not the government contracting officer, although the contracting officer can challenge or query the determination.    Read all of DFARS 215.371, is the value of the subcontracted action under the SAT?  That would be an exception.