If you have a wholesale store and multiple retail stores, you can e.g. set the wholesale store to be the main merchant and the retail stores to be additional channels (sub merchants).
You can add as many additional channels under your main merchant as you have sales channels. The products are stored in one stock and you will see one list of products.
You will also see one list of orders, but the sales channel name is visible on the order list. You will receive one invoice from stock and separate invoices for fulfillment and delivery. There will be separate sender names on shipping labels.
All channels and integrations are under the same main merchant page. After the main merchant is set up, go to Edit merchant → Integrations and click Add additional channel. Type down the sender name and save. If the Secret token is missing click the Regenerate button to create one.
Open up the additional channel page and fill in the channel information.
Add a new integration on the Edit merchant page and choose the additional channel. You can find here the integration instructions.