Actually, what you're describing has very little to do with the game, or the game-mechanics, or roleplaying. It is simply a matter of team-management.
However, thankfully there is a nice, roleplaying-based solution for handling it.
Some game-worlds have areas or countries which require bands of armed adventurers to officially register, so that you don't effectively have little private hit-squads running around in the world causing havoc without any way to know who they are. In D&D, the Forgotten Realms talks about Adventuring Charters for your party. These provide a list of who is in the adventuring Company (character list), and the rules for staying in the company, the rules for dividing loot, the rules for conducting business, etc.
Real-world examples would be things like the Hudson's Bay Company - an adventuring/business company chartered to set up business opportunities in Canada and the New World, and whose charter became a sort of impromptu backdrop for its members' behaviour in their new foriegn home.
Have your players officially write up their charter. Come up with their rules. It is their company, so they should make up whatever rules they want. Do they want a democracy? Do they want something different? Rotating shifts as chairman? Make sure that they include rules for dealing with money, loot, found items, specific types of items, items which cannot be easily divided or sold, etc. Make sure that they include rules for how to dea with anybody who BREAKS the charter, including first offenses, etc. Make sure they get it all written down. All of it. Write it down. Then sign it.
It is fun! Believe me! Have them do it via e-mail, back and forth, arguing over the wording and quibbling over details.
Then, they sign it, and the game starts.
When the loot shows up, the rules are clear, and they know how to behave. If somebody breaks the rules, the Charter comes into play, and they all know it.
Suddenly your problems disappear, and loot is no longer an issue.
And more to the point, you've had a cool out-of-game roleplaying activity which has become a cool in-game team-bonding exercise.
And if you're lucky, your adventuring Company can make a real name for itself!