Multiple seating on a mount

Has anyone seen a snippet or does anyone know of a system that allows for more than one rider per mount? I would like to see this so I could add open carts and carriages and such to my world.
For instance, four players could 'mount' a cart (a mob strung to look like a cart), and one of them use the command 'rein' to take control of the movement of the cart, just like a horse. Control of the reins could be passed to another simply by typing 'rein' again, thus loosing the reins of the cart so another could take them by using 'rein'.
Anyway, anyone heard of code that allows multiple seating on a mount?
Gadush

You could just add a linked list to mobs and treat them as "passengers", as it were, and add a check through all the mobs passengers whereever its property. You could still easily set a characters mount pointer.

Make the mob, set the pet flag, make an object so they can buy a horse, then go next door to buy the carrage, set a prog so that when mob X goes to rvnum, trans ovnum and everyone seated to rvnum as well. Fair bit of mud coding, and tying everything together would be a bit of a trip, but still, might work