When you say "80% of the stock is the same", I want to clarify which of these two scenarios you are describing.
Scenario 1: 80% of the global item catalog can be found at any and all stores, and 20% of the catalog is exclusive to certain stores.
For example, if you have a global item catalog of 1000 SKUs (what RMS calls the Item Lookup Codes), 800 of those SKUs will be carried by all of your stores. In addition, 100 SKUs are only carried in store 1, 60 of those SKUs are only carried in store 2, and 40 of those SKUs are in store 3.
Scenario 2: 80% of your inventory can be found at a given store, and 20% at another store
Example: you have 1000 SKUs, and at any given time, you have around 5000 units of inventory.
Store 1 is your “flagship store” and carries 80% of the stock (4000 units), and the other 20% is distributed among your other two stores.
Remember, when you're dealing with a multi-store environment, 100% of the item catalog must be created and maintained in Headquarters.
Once you have created your Headquarters database based on a given store (say store 1), any item lookup codes which were in your other stores but were not in store 1 will not have an associated item record in Headquarters, so they are effectively orphaned in your stores. Items added or changed at a store level will NOT upload to Headquarters.
Your template store (which you will use to create your HQ database) should contain all of the items, customers, etc which could possibly exist at any store, even if the inventory level at your store is zero.
Once you have the full item master catalog in Headquarters, you can then send the item master information for some or all of the items down to the stores (which is scenario 1).
You can even send the item master information to a store which will never carry that item in inventory. (scenario 2) The store would have the item showing in their item lookup, with a quantity of zero, but you can then do a Check Stores on it and see if there is any inventory for that item in the other stores.
Bill Yater
Blue Horseshoe Solutions, Inc