Okay, so, I guess I'll make some suggestions that are in good keeping with that little thing called reality.
Suomi Kp/31; Those were used by Germans. In limited numbers, yes, but this is the game that has the AVS, the MKb42, and G41 (which was prone to breaking quite often in trials), none of which were ever fielded. The Kp/31 was a Finnish submachinegun on which the Russians based their PPD-40, and later, PPSh-41 submachineguns. It was a rather heavy milled 9mm SMG (so maybe code it to have less recoil due to the weight, but much less penetrating power compared to the 7.62x25) which fed from 20 or 36 round stick magazines, 50 round "coffin" quad-stacked magazines, or 71 round drum magazines (which the Russians blatantly ripped off). This was used by some German forces, this I know, and I believe that they weren't issued the 71 round drums (don't quote me on that), but I don't know much outside of that. I don't know what the designation of it was, and I don't know who used it, but again. G41s and MKb42s.
Another couple of ideas which wouldn't be too hard would just be either Mp41(r)s or Mp717(r)s. Those were captured PPSh submachineguns, the latter being an unconverted type that was issued with 7.63 Mauser ammo rather than 7.62 Tokarev (7.62 operated at higher preassures, so the ammo could be found on the field). These were actually the second most common submachineguns that the Germans issued. Although I think it would be more worth it to put in an Mp41(r). That was a captured PPSh rechambered to 9x19mm Luger ammo, and fed from - I believe - the standard 32 round MP40 magazines. So it would have the standard German 9mm ammunition, and operate at the same rate of fire as the PPSh did. Once again, I'd suggest changing the ballistics to that of 9mm.
I'd of course like to see some of the classics come back, though. You know, like the Gewehr 43, the MG42, the Luger, the PPS43, the Panzerfaust... You know, that fun lot.
If this stuff has been suggested, I'm sorry, I haven't been keeping up with this at all. I've been a bad fanboy.