In the present paper we address the problem of synthesis and integration of chemical reactor networks into the overall process when separation and heat effects take place simultaneously with a complex set of reactions in a reactor system with multiple multicomponent feeds. To solve this problem an algorithmic procedure consisting of two stages is proposed. In the first stage a reactor network presentation which involves series-parallel combinations of differential sidestream reactors with intermediate separations has been used to generate a comprehensive set of process alternatives. Optimal process configuration and parameters have been obtained in the second stage with the use of conventional optimisation techniques. The present methodology has been derived from basic principles of reaction, mixing and separation. The use of the proposed methodology has been illustrated in detail with a simple example problem.