InfoPath Dev

I am looking at a solution to have 1 form, but based on choices made on that form, a submit button that sends it to a specific form library. My question is, do i need to create a form library for each 'destination' and update the form libraries everytime a change is made, or just update the 'source' library?  The 'source library' won't actually get a form submitted to it.

You can just update the source library - if you look at the XML files submitted to the destination libraries in a text editor, you'll see they have an href attribute that has the URL to the form template - and that will be the source library.