controlling

hello,

The Scenario is: i have a controlling area and 4 profit centers. like i paid travelling expenses. i want to allocate this exp to four profit centers in 40,30,20,10% ratio , further i want to reallocate this ratio to our 4 customers, like 50% of 40 to A customer, 20% of 40 to B customer, 20% of 40 to C customer and 10% of 40 to D customer. system allocate automatically this cost to profit centers and after to customers but in equal propor tion.

plz suggest step wise.