How a Google Sheets Inventory Bug Lets Shared Kit Parts Oversell Stock

A common Google Sheets inventory setup assigns each SKU its own quantity row, but this breaks down when two product bundles share a component. If Desk Set A and Desk Set B both use the same body part, the sheet counts that body's stock twice, allowing more orders than physical inventory supports. The oversell only becomes visible days later as a cancelled order, since the spreadsheet rows and formulas appear internally consistent throughout. A developer proposes replacing static kit quantity columns with a calculation that derives availability from the lowest-coverage shared component. Custom Google Apps Script functions enforce this logic by tracking committed stock across orders and blocking any sale that cannot be fulfilled from remaining free inventory.