i think that it is possible to play the game with alliances,
each player start’s the game independently, alliances can be formed for capturing territories, or defending territories,
if a player agrees to reinforce another player’s attack ( there is a house rule that allow’s player’s to reinforce for multi-national attack / ) or defence, the player’s concerned could divide the i.p.c. captured or held by negotiating the value among themselves,
some thing like a free for all, with the idea that alliances could be formed,
i would determine victory by last alliance standing / or a set number of victory cities
player’s could form alliances, or go it alone,
if you have lot’s of playing pieces, from other edition’s of axis and allies, you could have up to 10 player’s in a huge free for all, with alliances being made,
if you lend some of your force to a player they would take command of that force, and it would be that plkayer’s initiative to send it back or use it, these forces could not be used to attack the same alliance, or their original power,
they could however be captured, by the player that wanted the alliance, and used as hostages,
i think that a rule set would be fun,