At current on-line shops, buyers almost independently enjoy shopping without anyone's help. However, there are many cases where they cooperate with people such as personal advisers or salespersons at real shops, especially at apparel shops. In the process of cooperation many evaluation data on candidate products are exchanged between buyers and personal advisers. These evaluation data can be used for various services and marketing activities at the shop side. We propose a shared discussion space for cooperative users by sharing information on candidate products and evaluation data on them. The shared discussion space provides a dynamic configuration mechanism from many viewpoints of criteria in order to help buyers to decide which item to buy.