Below is the response to the FAQ issued by OMB related to this topic:
"It is acceptable to have more than one fixed amount subaward with the same subrecipient if necessary to complete work contemplated under a Federal award. It is expected, however, that each fixed amount subaward will have its own distinct statement of work and be priced for the work and deliverables that will be due under that subaward, and that prior approval of the Federal awarding agency is required for each subaward issued under funding received on or after 12/26/14, as outlined in 200.332. Non-Federal entities having special circumstances, including an unanticipated need to increase a fixed price subaward above the threshold, should consult with their Federal awarding agency for guidance on how to complete the planned scope of work with the least amount of administrative burden."