I have 3 pages in my website where user can either register register of login. On each page the amount of data required for registration is different. Problem is that i need to use webforms for the user registration pages and create 3 different forms with different level of data being asked. And when the user enters his email ID in the registration form, if he has already submitted the form once, his previous data should be filled up in the user registration for editing purpose.
Webform isn't the right choice here because Webforms are designed for multiple submissions against a template. You seem to want to extend/create user profiles and include these fields in registration. I recommend you use the Profile 2 module instead.