Modern supply chains differ in lead times, bottlenecks, and demand volatility. Advanced Planning Systems conventionally decouple Master Planning (MP) and Demand Fulfillment (DF) hierarchically, which improves tractability but ignores critical interdependencies between material availability, capacity utilization, and delivery promising. We propose an integrated MP‑DF model, formulate it as a Minimum‑Cost Multicommodity Flow (MCMCF) on a time‑expanded graph, and compare partial and all‑or‑nothing fulfillment policies in a dynamic rolling‑horizon simulation. For single‑commodity orders with priority‑based penalties, partial fulfillment achieves service levels and delivery punctuality indistinguishable from the all‑or‑nothing policy while reducing runtime by more than an order of magnitude.