While you might not get the final say in all matters, your client hired you for a reason: to provide guidance. So, guide them. It involves providing a solution, hearing their feedback, and suggesting alternatives. If they want to see it another way, do it that way.Explain your reasoning. Discuss the pros and cons of varying options. Note why you have concerns about certain approaches. Discuss what the implications might be to their businesses. Your goal is to produce a solution that works for them. Sometimes clients will request approaches that make it harder to reach those goals. At such times, suggest alternatives—but let them make the decision.