i think i have a solution, how about capping the lowest server playing out of the 3 playing, say red team is lowest with 50 people on so green and blue has cap of 50 which the cap lasts for 30 mins and then refreshes so if more join and more people join and the lowest is now 70 then it caps to this then refreshes after 30min and repeats
or if lowest server has 50 people then add 10 % increase to others so it not too much out of favour and is playable, what do you guys think?