I have yet to come across a document giving the exact definition of SA, I sort of go Supplemental Acquisition. Kansas City only ever had 1 contract for B-25 which the USAAF kept extending, initially for 1200, then another 1325, another 1050, another 2800, another 206, another 359? Inglewood received new contracts each time, not extras on an existing contract. Note the final Inglewood contract date and the Kansas City supplements begin.