we need more players to join the server to have a third faction.
simple math
50 players/2 = 25 per faction
50/3 = 16.67 players per faction.
Now if we have 75
75/2 = 37.5
75/3 = 25 per faction.
50 Players and 2 factions is the same for 75 players and 3 factions.