Can Country be automatically set depending on value in States dropdown?

Per this post http://www.gravityhelp.com/forums/topic/display-us-states-and-canadian-provinces#post-67866, rather than use the Advanced Fields Address group, I created individual fields so I could use a custom list for a States / Provinces dropdown that i needed. Works great!

Now I'm wondering that if the user can only select a valid state/province, why am I asking him to also tell me what country he is from. By deduction I already know that. Plus I'm opening up the door to inconsistent data. The user could enter New York City, New York and then select Canada for the country. I think that my form needs to be a little more intuitive.

The reason that I don't delete the country field altogether is that it is useful on "List Entries" screen on the WP Back-end where I can quickly get snapshot of what country my entries are from.

Based on the value selected in the States / Provinces dropdown mentioned above, is there a way that I could set, via a hook, an Admin-only field (like a checkbox) that would indicate what country the user is from? Or even a hidden field?

Thanks!

Thanks Chris for your prompt response! So what you are telling me is that if I want to build a form OUTSIDE of GF then I could use a method such as the one you linked to. Within GF there is nothing, currently that I can do.

I was hoping that there might be some hook available (e.g. when the state field was saved) that would allow me to query the state field and then update an admin-only country field.

Anyway I'm probably just going to put the country dropdown back on the form and just live with it. Thanks again.

If I do something like suggested here...
http://www.9lessons.info/2010/08/dynamic-dependent-select-box-using.html

Is there a way / what is the best way to pass the values into hidden fields in gravity forms?

Is it better to pass by value or reference? Obviously by reference if the user changes it but.... if they don't is there an advantage either way.