I saw the Size of Army Units in WWII when I was searching the site as well as your comments in another thread and didn't see anything like the platoon HQ. I had the gentleman go over it a few times on the phone as that was the first I had heard of anything like that. So, the 157th as you mentioned, did have the three companies (A,B and C) as well as a Headquarters Company, but it seems that they also had this platoon headquarters as well, perhaps one for each of the companies A, B and C?
I was able to find this gentleman in the After Action Reports, Rroster of Officers as 2nd Lt., and called Platoon Leader and Mess, Suply, Trans under Bn Prin Dy (which I assume means Battalion Principal Duty?). I guess the Mess, Suply, tran(sportation?) factors into the platoon HQ?
My list of questions for him is growing by the minute!
Thanks Marion