I'm trying to understand something - some facts first:
If a new member sign into my site, he's created on my members list, and on my contacts list.
When booking an appointment to a new client, a new contact is created automatically.
I booked an appointment with John (for example only) witch is not a member on my site, and a new contact has been created automaticaly with name, phone AND EMAIL.
Now the important issue: If John wants to sign in as a member WITH THE SAME EMAIL ADDRESS, a new contact is created in my contact list, and synced to the new member on my members list. It means that i have on my members list one member named john, and on my contacts lists i have 2 contacts named john, with the same email address, while one of them is synced to my member John.
How can i avoid duplicated contacts?