"As each customer will only likely have one referral source, it should be safe as long as there is correlation. In this case, I would be willing to bet there is a very strong relation to referral source and customers where someone will want to know how many customers came from what referral sources."

yes this will be required, but they will also want to know how many orders came from a referral source which is when the party leaders referral source would be inherited by the party members. Im doing a transform on the fact order using the dimcustomer for this just now but i think i may be able to build this as a measure into the cube?