I think it is much more interesting to have alliances be created based on factions, power, and technology. There is a very complex system behind the diplomacy levels. I am currently trying to work it so that two weak, like-minded, factions will become allied and then declare war on everyone else. It's hard to do, since the likelihood of an alliance can't be manipulated. All I can do is make the two factions like each other alot in the late game if they are both losing. That should work, but it needs testing.
Now that I realize this is not in the modding forum, I will silence myself. 
