A couple of minor corrections/clarifications. The schwere Panzerjäger-Abteilung 653 consisted of two companies of Jagdtiger. They were never known as "Tiger III". Division zum besondern Verwendung (z.b.V.) Division Rässler was a "special employment division" organized 11 September 1944 to command the rear area of Korps Feldt in operations against the US 82d Airborne Division. Korps Feldt was an ad hoc formation organized from the Ersatz und Ausbildungs (replacement and training) and security units of Wehrkreis VI (Military District 6). It was reorganized 28 December 1944 as an element of the LXXXIX Korps of 1. Armee in the area north of Lauterburg. It was "professional" and was not really "static", but was a line of communications unit, so yes, was not meant to provide infantry support. As Alsa.se noted, sources indicate that 7. FJD was on the line Sessenheim-Dalhunden-Drusenheim when it went into action in January, but that does not mean that various detachments would not be assigned to support the attacking elements further north.