I ran into a problem a little while ago that might be a solution here.
I had multiple address fields and if the "Same as above" check box was checked, I'd disable the second set of fields and update them with JavaScript if the user changed the details of first set of fields.
The problem was that the updated second set of fields wouldn't be saved when the document was submitted. I solved it by re-enabling the fields when the user clicked "Submit".
I don't know if the enabled/disabled property is something that Firebug could be used to change as well, simply adding one more step to the hack.
I ran into a problem a little while ago that might be a solution here.
I had multiple address fields and if the "Same as above" check box was checked, I'd disable the second set of fields and update them with JavaScript if the user changed the details of first set of fields.
The problem was that the updated second set of fields wouldn't be saved when the document was submitted. I solved it by re-enabling the fields when the user clicked "Submit".
I don't know if the enabled/disabled property is something that Firebug could be used to change as well, simply adding one more step to the hack.