Dynamic Population with data in different form

Hi all,
I'm workin on the different form that i'll call MYFORM_1 and MYFORM_2.
is there any possibility to dynamc populate a specified field of MYFORM_2 taking data from MYFORM_1 where the e-mail address is the same?
I use MYFORM_1 to register user with First Name, Last Name, Address, City, e-mail, using User Registration Add-on (where email=username).
Then i create a second form MYFORM_2 visible only to connected users. So i've a first hidden field "Username" with Inserted Merge Tag {user:user_login} that give me the user's e-mail address.
Having this e-mail i want to dynamic populate other 3 fields of MYFORM_2 with other data of the specified user (by e-mail) stored in MYFORM_1.

How can i solve this situation?
Thanks in advance.

I think it's not useful for my case that tutorial.. I would to call meta data stored with an other form.
The query string method it's not useful i think.