We find that people will king-make a lot in this game if they know that person X will win; so they end up ciding with that player.
I'm thinking that trade should only be restricted to those people you have equal footing in trade.
Merchant and Traders are affected; you can only trade or merchant if at same diplomatic level only.
I will certainly think of playing this to see what happens.
What a strange group thing to help the person, who is winning. I almost always see alliances against the leader (in all kinds of games really and not just this one).
Edit: Though interesting to restrict trade a bit, as the discussions can go on for quite some time.