Sales and operations planning (S&OP) is the most appropriate methodology for synchronizing supply and demand across the supply chain for a group of trading partners collaborating to improve customer service levels and profitability. S&OP integrates and aligns the production, financial, and sales functions within a company, providing a comprehensive view of demand and supply. This collaborative process helps in balancing supply with demand, optimizing inventory levels, and improving overall supply chain performance by ensuring all partners are working towards the same goals.