a reward unit can (or should) always only replace one unit and should work in the same class like the original unit
eg: if you want to replace the pak40 (which is at only) with a reward unit you cant replace it with something which is good vs at and ai
also its not working to replace 2 units with only one (especially when these units are from different tiers)
but the good news is we already have 2 reward units for ostheer

and the plans for the last rewards are close to the end
