You can display the URL of the iframe in the browser? Or some parameter in the URL when accessing it falls into the page I want the iframe?
Example: Iframe: http://mysite.com/members
My page containing the iframe: http://mysite.com/account
If I navigate within the iframe to another location http://mysite.com/members/register wordpress will continue http://mysite.com/account. If I reload the page or passing the address to someone, the iframe will be loaded http://mysite.com/members again.
So might have some parameter, if I navigate within the iframe, the URL changes and so if I reload the page or pass the link to someone, you go to the page of the iframe correctly.
Can be of type: http://mysite.com/account/?url=http://www.mysite.com.br/members/register I've seen working on another site.
I'm sorry for bad English, I hope you can understand.