Hello MadDog and Jan-Hendrik !
The Information given by Jan Hendrik is confirmed by Scherzer.
According to that work, Maj. Werner Rätzer was Chef of Feldersatz-Kp. 200,
(also designated as Div. Kampfschule), from some unknown time in/after
August, 1944 to at least November 1944.
In November the unit was expanded to Feldersatz-Btl. 200 with Stab and 1.- 4. Kp.
Both units were part of 21. Pz.Div.
Kampfgruppe Usedom however is of different origin. According to Bettinger,
Die Geschichte der Hgru G, p. 183, this unit consisted of two battalions,
II./104 and II./115, which escaped the Mons pocket, where their parent unit
47. ID was smashed.
It is mentioned two times, under command of Pz.AOK 5 :
- On 23. Sept, fighting 30 km west of Nancy, in the area of Domjevin and Veho.
- On Oct., 1st, it is stated that regimental group Usedom is attached to XXXXVII. Pz.K.,
after having been subordinated to Gen.Kdo LXVI. (area of St. Die, 60 km SW of Nancy.).