In response to the question "How did this come about?", let us consider this:
The 13th A/B DID include the 326th GIR, and was credited with a single campaign, Central Europe, 22 Mar 45/11 May 45.
The division had a very short tenure in ETO, departing NY P/E, 26 Jan 45, arriving France, 6 Feb 45 , arriving back at NY P/E, 23 Aug 45, having been located at Auxerre, France, the first of that month.
The 82nd A/B included the 325th GIR.
That division was credited with Sicily and Naples-Foggia in MTO, and Normandy, Rhineland, Ardennes-Alsace and Central Europe in ETO.
It was located at Ludwiglust, Germany, at war's end.
If you have access to your dad's Separation Papers, they will register his campaign history (Medals and Awards), which should a least resolve which A/B division he served.
Once settled, you are going to deduce that he was in 326GIR/13A/B, OR, 325GIR/82A/B.
This doesn't help much, I'm sure, but I tried. OK ?