Thank you Andy for your response.
Leadin is a valuable plugin!
To include the already registered users seems so natural to me.
What I see…
On the Leadin settings page there is a checkbox: “add existing WP Users to Leadin”.
1.) The first time the box gets checked and saved, you iterate through all WP users and add them to your Leadin database; and add a flag: “imported WP user”.
2.) After that you hook into WP for users being added, edited, and deleted and sync it with your Leadin database.
3.) If for any reason an Admin deselects the checkbox on the settings page then you iterate through the Leadin database and remove all users with the “imported WP user” flag.
Andy, please excuse me if I make it sound so easy; I am aware that this feature would require several hours to develop and test.
Thank you again for the plugin,
Holger