Magento 2 MSI: How to set salable qty for product

When a user places an order for item A, qty 1, I want the order to ship to all the addresses in the user’s address book.

I am able to achieve all this. However, since I’m creating the shipments programmatically, I can set the qty for each shipped item, which results in the correct reduction in Qty Per Source. But the Salable qty always reduces by 1.

If there are 5 addresses in his address book, the salable qty should also reduce by 5 and not by 1.

How can I do this through code? Thanks