I am working on development of a live auction site, where multiple sellers will be able to list their products for auction and the buyers will be able to bid on the products real time. The user with the highest bid will be announced as the winning bidder. Once the winning bidder is decided an invoice will be automatically generated and the user (winning bidder) will have to make the payment within a certain time frame till the invoice is valid. Once the user (winning bidder) makes the payment, I want to split the payment in two parts: 1. The administrator of the site will get the site commission and 2. the seller gets the remaining payment. The calculation for the split of the site commission and seller's part is already done. We are trying to use Adaptive Paypal (X.com) for the payment gateway to receive the payment from buyer and the split the payment for the site commission and seller's part. For this we have set the Administrator as the Primary receiver and the multiple sellers as the secondary receiver, because the administrator will be the common factor in all the transaction.

However there are couple of problems with this solution. These are:
1. X.com will not allow us to keep the administrator as the Primary receiver. They want the sellers to be set up as the primary receiver, because:
a. This way the Sellers will be Merchant of Record and therefore responsible for any chargebacks / refunds arising from usage of the application. If the administrator is the Primary Recipient, he would be responsible for refunding 100% of transactions, even though he is only holding a small percentage of them. This is not acceptable to PayPal.

b. If the administrator is collecting funds on behalf of sellers (even temporarily), this constitutes Fund Aggregation which is strictly prohibited by PayPal due to their Financial Regulatory constraints.

2. The other problem is that in the application that we are submitting in X.com for their approval, there is only one field to enter the details of the primary receiver, which we have currently set up for the administrator of the site. Also this field is fixed. So we can not set up it to accept different sellers for the primary receiver's field for each transaction.

Any suggestion how to resolve this problem? Or how it should be implemented in a multiple seller model.