Michael, we are a day away or so from a final version of our announcement for the "Bitter Ender." Cool (hopefully no snow) that you are going to the Scandinavian Open. I have went three times in the distant past. These days with nieces and nephews in Germany, I must confine my foreign travel to there but fortunately the Grenadier tournament is again being held.
The removed units come from the Reinforcement Group whose entry area you exited from. The entry areas don't overlap, so removed units can't come from both groups, only one of them.
Have fun.
Tom