Blue Onion is a financial reconciliation platform focused on the order-to-cash lifecycle — tracking orders, payments, and bank deposits through to journal entries. It does not track physical inventory or warehouse-level data, so shrinkage (losses from theft, damage, counting errors, etc.) is not something that can be tracked within Blue Onion.
For shrinkage tracking, we'd recommend using your inventory or warehouse management system (such as the NetSuite inventory module or your 3PL). Any shrinkage adjustments would then be posted as a manual journal entry in your GL.