Wikipedia tells us, that:
Following the unconditional surrender of the Wehrmacht, which went into effect on 8 May 1945, some Wehrmacht units remained active, either independently (e.g. in Norway), or under Allied command as police forces.
So between May 1945 and September 1946 the Wehrmacht still existed. As far as I know, some units served directly under allied command e.g. as police units (and some continued to due so even after the official dissolution of the Wehrmacht as newly formed organizations).
However, while there still was a Wehrmacht, what did the units do all day long? How were they fed? Paid? When they disarmed themselves, how did they acquire the necessary supplies (e.g. fuel)? How was discipline and authority maintained? Were Wehrmacht units allowed to defend themselves? How did the command structure between the allies and the remainders of the Wehrmacht work? What did a typical, say division commander, due to fulfill his orders (and how did these orders reach him in the first place?).
I assume that there is a whole lot of source material here (starting with written orders, files, letters etc.), but I cannot find anything.