ya its not a guarantee by any means. Like I said earlier, given that they aren't sexed and can't easily be sexed, the more you have only raises the chances of pairing off. Getting rid of any will simply give less choices for mates. I think you could capitalize on the fact the the two troublemakers are so much larger than the rest. Chances are that those are the two dominant males of the group, by dividing them and allowing the others to get through the divider would be the best call IMO