I have inherited support of a website that uses session variable extensively to store user selections, the site is ASP.Net with code in VB.Net

The site is being accessed by some clients via an iFrame, which gives me an issue as in some browsers the sessionID is lost between pages when within an iFrame.

I have been looking at various options like using querystrings and/or ViewState, but both of which have advantages and disadvantage but this is not my normal area, so would appreciate any advice on which might work best?

Alternatively is there anyway to pass a session ID or in some way get the session to persist between pages?

Gary.