If you are running multiple sites that share a common root domain, it is easy to setup a system where logging into one logs you into all of them.
Designate one of the sites to be the master site.
For the other sites, go into
config/othersite.mydomain.example/0_site directory, and remove the
users and
sessions directories. Now create shell-links to the directories of the same name in the master site.
Then, in all the sites, go into
config/sitename.mydomain.example/0_site/settings and edit the
server.txt file. Add the following line:
cookie_domain:mydomain.example
Substitute the mydomain.example for your own domain.
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