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

You did not give the reference you believe gives you leeway to request a waiver.  Nor did you identify what is being acquired or any other pertinent information.  As a general approach, when the US Government is acting as agent on an FMS contract, acquiring for a country the same thing the US is acquiring, we get for the country the same as we pursue for the US to the extent that is what the country wants.

A QASP is not a contractual requirement, and thus the FAR would not be addressing the QASP specifically.  The QASP and its execution during contract performance is a matter of negotiation with the contracting office and the country for which you are acting as agent.  This would appropriately be part of an LOA/MOA/MOU not the contract.

DFARS 246.406 speaks to use of Standardization Agreement (STANAG) 4107 when dealing with NATO countries.  It also addresses non-NATO countries.  The AFARS is silent on the matter.

With regard to developing a QASP, we assume it would be relatively simple to tailor the QASP the US uses or offer the QASP the US uses to the country for their sue/tailoring.