This plugin works with any users name and the user ID doesn't matter, even the permissions do not matter (although the admin can do some things more).
If you change the user ID in the database manually, then it won't work, but how coulld it?
If you manipulate the database yourself, you will have to manipulate the records of the plugin too.
The same applies if you delete a user. If you deleted the admin user that enabled 'Share with all users' option, there is a solution for that in the FAQ.
Again, this plugin works with any user name and any user ID as long as you use WordPress to manage users.
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