Hello,
Is it possible to make a single sales invoice and include inventory items from various inventory locations
I think in this case, you should use separate New Delivery Note for each inventory location. This way it better maps what is actually happening in your business (I assume each inventory location is making their own delivery arrangements separately).
Also, make sure to create New Sales Order before and then select this sales order on your invoice and all delivery notes. Sales Order will track your delivery status. This makes sure that all ordered items are invoiced and delivered.
See: Manager.io