With Orange Manager you can easily ship just a partial order by viewing the Drop Shipping / Partial Order Shipping section of your Order View Page.
This is located on the lower right side of every order page.
There you will select an option from the drop down. This dropdown includes both drop shippers, and your local warehouses.
You'll slect the warehouse and then select the item(s) to ship.
Just follow thru on the buttons to add shipping info and your all set!
Orange Manager will mark which items have shipped, and display them when you return to the order view page.