Look..... if they drop off map we either cluster them all just around where they theoretically landed or we teleport them to the center OR we just removed them from play and call them dead. We decided after previous experience with scenarios and campaigns that involved paras, that since para drops are notoriously scattered anyway players should be HAPPY units that would have landed off map were brought back in play.
If you want to avoid this "problem" then don't drop paras close to the map edge in low visibility otherwise they will end up in the middle of the map. That's the way the game works. Accept it becuse it's not going to change