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 senders (sub merchants).
You can add as many additional senders 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 senders and integrations are under the same main merchant page. After the main merchant is set up, go to edit merchant page and click "Add additional sender". Type down the sender name and save.
Open up the additional sender page and fill in the sender information.
Add a new integration on the edit merchant page and choose the additional sender. You can find here the integration instructions.
On the order list view you can see the orders from different merchants.