Just a tip for any low/mid-level Guilds attempting to get the 'Team Synergy' console Achievement.
Coordinate with your guild mates to hold off donating significant amounts of Gold for 2-3 Weeks. In addition they should not rank their Kingdoms at all during this time. Once you have enough together put it in all during the same week.
If, you don't have a full roster of 30 post what you are planning as there are always 'Achievement Hunters' to join for the duration.