What if I buy Panzer Corps on Steam, but I already have..

[smashtheaxis]

.. bought Afrikakorps & Allied Corps outside of Steam? I guess I would not be able to have them together in the same install? Should rather buy PC also outside of Steam?

[Tarrak]

If you bought your PC from Slitherne or Matrix you can redeem your Steam key and register the game on Steam. Due to Steam's technical limitations tho you will need PC:Wehrmacht as base game before you are able to redeem the AK, AC or the GC DLCs. I think in your case the easiest and best would be to buy PC:Wehrmacht from Slitherine and redeem all keys and register them on Steam. This way you can have the game either just installed normal way or per Steam or even both. Whatever you prefer.

[smashtheaxis]

Great, thanks. I did like you suggested and bought it directly from Slitherine.