During the bidding process a couple {product; projects} has to be formalized. To be competitive, the bid should present an innovative advantage While being achievable. Most often the time, if product is complex, a unique company doesn't have the whole competences to provide the complete product. Depending on the selected partners, different possible innovation level can he reached. This decision also influences the level of risk of the project. To he profitable, if the bid process is successful, the best couple \innovative product; reliable project\ has to he selected. In this paper we present a decision support system :for making alliances, based on a Decision Tree. The originality of the paper is to consider linked decisions focused on the collaborative network and on the risk management.