Hi @studio-umbrella ,
Depending on the carrier you are using, but Ship&co application allows you to combine orders and make a shipment. Ship&co supports major carriers such as UPS, FedEx, and DHL. Please see this link how the process is done inside the application. After combine the ordered items, tracking number & order status will be sent back to Shopify store but in such case, if you have two orders combined, you will have to fulfill one order and mark it as shipped manually.
It is completely free to get started since you will start 14-day free trial right after signup so that you can try out our services without any charges and without payment information.
See more info from the links below:
Hope this helps give you some idea how it works!
Best,