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.

Yes.  When doing an FMS case we are the agent of the country.  We act in the country's behalf just as we would for ourselves.  All the same caveats apply.  As much as possible, put less than the allowable amount on the UCA, set a definitization schedule of less than the maximum 180 days, and put the contractor on notice that the work done before definitization is by definition less risky and therefor will earn lass profit.  Reread the guidance and direction in DFARS subpart 217.74