What are set up steps so that users with two accounts can toggle between two troops?

I manage items for two troops, and my account was set up using the same user name and password so that both are somehow connected. I can click on my name and toggle over to the other troop by using the ‘Go to ___’ menu item. How do I set this up for others? When I set them up with one Troop, they are given a username. Then, when they are added to the second troop, they are given a different username. Then, they go in and change their second username to match the first one in their profile. Then, they have no access to view anything in the second troop. What are we doing wrong?

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