After studying the four PFDs provided, combine all of them into a single Mixed Model Process Flow Diagram that incorporates all the processes and process relationships. Be aware that not all products will go through all processes. We suggest starting with the most complex PFD (incorporating the most processes) and overlaying the others, working upstream. It is frequently the case that the less common processes occur upstream; think of them as tributary streams flowing into a large river. We suggest working with a Post-It note labelled for each process, laid out on a large sheet of paper.