A method and system are provided that enable partner sites to join in the sale of products/services via an on-line group-buying sale business method. A seller registers a list of products/services to be displayed on partner sites. Customers/visitors who access partner sites may link to one or more on-line group-buying sales conducted on an owner's main site. Accordingly, the method and system enable a super demand aggregation for products/services offered for sale by the on-line group-buying sale business method. The invention provides a partner menu tree that allows partners to pre-select products/categories for display to customers linking to the on-line group-buying sale from their partner site. Sellers may provide particular products, services, categories, and abstract terms to help partners select which products/services to display for customers from among all the on-line group-buying sale products/services. The invention has applicability to sales paradigms other than the on-line group-buying sale business method.