distributor extensions ?

Hello,

I'm looking for extensions to support a distributor model. We are a country wholesaler and customers come to our website to place orders. We have many products and we'd like distributors per product line. A distributor may be assigned a region, a province, a city or institutions within a city depending on business needs. We'd like to associate customers to distributor based on addresses. When a customer places an order, it is associated with the relevant distributor. Are there distributor extensions that meet our needs.

I'm aware of customer group and (MTA) affiliate. Neither of these meets our needs. Customers could place an order without registration or a referral, and distributors do not overlap in terms of geographic coverage.

Thanks.