Add new instrument to xml imported file

How do you add a new instrument to a XML imported file? When I add an instrument in setup, it creates a new flow. I want to be able to add a new instrument to the imported .xml.

An added Player/Instrument should end up added to all flows.

How are you adding this instrument?
Did importing the XML create an additional flow (to import into) and leave your original flow empty?

I created a new project with just a drum instrument. Then I imported the xml which created a new Flow in the project. When I added a new instrument, it adds it to the original and not the imported xml.

That is true when you have created two flows inside of Dorico. However, if you import a xml and have an existing flow, new instruments are not added to the xml.

Figured it out. You have to have the flow boxes both checked and the new instrument will extend over to the xml.