You can (if you're using the Financials module) create multiple Charge Codes, which can apply at the Task level. You can, for example, have one Charge Code that is applied to the Labour task which splits the billing for that task 4 ways, and another for (e.g.) infrastructure purchase which sends the bill to a specific customer. Be warned, though, that this is a slippery slope and there are many points of failure. The first is that it relies on the Project Manager entering the correct Charge Code against the Task; there are no automatic checking mechanisms within any of the Clarity jobs to ensure accuracy. In my organisation we have been grappling with this for 3 years now, and still haven't managed to conquer it.