Need help with login of user for site and blog - Mixup & Confused

Hi, I’ve a site where I want to add artist. For that I’ve created an artist database which is updated by user itself. As the artist page is just for members so I add a login button too. But this login button automatically links with the Wix Blog which has different database for email & other details.

Now, the problem is, I want to fetch the data while updating the profile of a user. If a user login to the blog then how I can fetch the email id and compare it with the artist database.

Thanks in advance. If anything unclear then let me know I will update this.