Think of three layers:

1. Delivery dates - your kitchen's calendar. Retail menus, wholesale ordering and the Retail Dropoff Report only use dates that fall on the kitchen's Retail / Wholesale fulfilment weekdays; Grab&Go customers only see dates on a location's Grab&Go Open Days.
2. Quantity Needed - a dated plan per location, meal and portion (the Retail Menu). It drives the Retail Dropoff Report and is what Update Stock / CSV uploads write.
3. On-hand stock - a single live number per location, meal and portion, independent of dates, changed only by stock movements (Update Stock, uploads, orders, refunds, manual removals, finishing a wholesale day). Grab&Go availability, the Stock Management page and stock alerts all read this number.

A typical day: set Quantity Needed (or upload it) -> kitchen produces and delivers using the Retail Dropoff Report -> click Update Stock at the location -> customers buy via Grab&Go and stock drops -> alerts warn when it runs low.