If you Mix Recordings with a friend and he has a secret base then you can go to it and battle him/her. If you mix recordings with someone and they have the same secret base as your other friend then you will have the second person's secret base unless you go to the computer in their secret bese and regester it. Then The person will always be there. Now if you want to have that secret base yours then have another friend with the secret base that you want open then have them move into the secret bese you want and mix recordings then have your friend move into another secret base and mix recordings one last time and the secret base should be open if you didn't have the person registered.