Form Validation

I "reopen" this topic, I was trying to make form_validation work after a redirection.
I understand this is a waste of resource, but here's the point : my controller method & view concentrate several forms (5) which I don't want to update at the same time.
For instance, I have a form with personnal info, another one with password, etc. I don't want to put them on a different page, I think it's not user-friendly to make him click time and time again.
So I made a "save" controller method for each form, but a single controller method to display the whole.
What would you do instead ?

Thanks for your help.