Increasing design complexity eventually leads to a design process that is distributed over several companies. This is already found in the automotive industry but SoC design appears to move in the same direction. Design processes for complex systems are iterative, but iteration hardly reaches beyond company borders. Iterations require availability of preliminary design data and estimations, but due to cost and liability issues suppliers often hesitate to provide such preliminary data. Moreover, companies are rarely able to judge the accuracy and precision of externally estimated data. So, the systems integrator experiences increased design risk. Particular mechanisms are needed to ensure, that the integrated system will meet the overall requirements even if part of the early estimations are wrong or imprecise. Based on work in supply chain management, we propose an inter-company design process that is based on formal techniques from real-time systems engineering and so called flexible quantity contracts. In this process, formal techniques control design risk and flexible contracts regulate cooperation and cost distribution. The process effectively delays the design freeze point beyond the contract conclusion to enable design iterations. We explain the process and give an example.