1. Change all the concerned products from "consumable" to "storable" (with an export/import).

/!\ What you need to do beforehand: make sure that NO OPERATION is in progress with these particular products. If there are some, you will have an explicit error when making the import. 

How do you make sure there is no open operation? 

--> Go in the Inventory app and check all in progress operations (deliveries, receptions, transfers, etc) and UNRESERVE the goods (you can easily do it with the 'unreserve' button). 

If you have too many operations to unreserve, you can also create a server action in the 'Action' menu to make your life easier, but be careful if you don't master this kind of task :p  

You can also ask your client to unreserve all his pending operations by himself as it is an easy task. 

2. Create/import all locations needed before importing the inventory adjustment. 

Be careful with the hierarchy of the locations and their routes (if they are any). 

3. Import the correct inventory adjustment:

- Ask in advance for an accurate inventory Excel file beforehand to your client (you will need to rework it before the go live so it's important you get it a few days before);

This file should mention: the correct product name/ID, the location (Odoo nomenclature !), and quantity. Don't forget the date of the inventory, it's really important that you get this right. 

- Once your file is ready, you can import it. 

--> NB Date of inventory: you can import retroactively a stock at a specific time, by mentioning the correct date in the field 'Forcing accounting date'.

4. After the inventory adjustment is properly imported, don't forget to 're reserve' the operations pending :) You can also ask your customer to do it ! 

What are my recommendations? 

• Products: for an unknown reason to me, the system doesn't accept easily the external ID of the products when importing the inventory adjustment lines --> I would suggest using the display name ([ref] name), it worked perfectly for me. This only my humble experience about it, I'm just mentioning it in case you're in the same situation so you can find the solution faster :) Other consultants using this methodology managed to use the external IDs :) 

• If you are in previous versions like V11, I would recommend creating a new menu with Studio with the model Inventory Lines (already existing in the DB). This makes the import much easier, but you have to create the empty inventory adjustment beforehand and click on 'start inventory' (see screenshot below)