If you have already sent an External Advancing Request, you yourself are in charge of it, and the only one who can approve the Request.
But! It's very easy to add a second, or third, approver.
This article will show you how to do so.
Request
Go to the request.
Click on the title of the Request you want to re-send.
Add approver
You can add someone from your team to (co-)approve the Request.
Click on the "+ Add approver" button to add the selected person. You can only select from the users that are in your Environment.
Be aware that once you have made changes, you have to press the Save button again.
Now that the second approver is added, the user will be able to see the Request in their own environment.
History
If you are unsure if you have already send your Request, and to whom, you can always scroll to the bottom on your Request and select the history.
Also useful: