One file, every supplier
With several suppliers, one file per supplier quickly becomes impractical. The master list is the Pro solution: a single file for your whole catalogue, where a supplier column decides which supplier each row belongs to. Rows with an unknown supplier are flagged as errors in the review — create the supplier under Suppliers first. The master list's column mapping is saved separately.
The Pro columns
The master list can also carry is_preferred (yes/no — preferred supplier for the product; also settable with the radio on the product's Cost & Margin tab — for variations in each variation's box — or in bulk from the product list via Edit → Preferred supplier; the product list also has a Supplier column and filter, and new supplier rows are added right on the product tab: pick the supplier, enter its cost, save), on_sale (yes/no — sale flag) and sale_start/sale_end (YYYY-MM-DD). As always: blank = unchanged.
The round trip
1. Export under Import → Export. The file contains all products with suppliers, costs, currencies and flags — product_id in the first column makes re-matching bulletproof. 2. Edit in Excel — adjust costs, switch preferred supplier, flag sales. Only touch the cells you want to change. 3. Import the same file. Only filled-in cells are applied, the review shows every change, and everything is undoable.
Template export
The template mode gives you the column headers without data — handy to send to a supplier who should fill in their price list in your format.