Hi CalmKz,
When the user opens a form for the first time, it has the SaveLocation parameter embedded in the URL. Opening an existing form, the URL will not have this because the form remembers it's save location. That might be related to issue that you are having. I think changing the Source parameter should do the trick, but looks like you are not getting the URLs to do the needful...
Are you using Content Types or regular form library?
More soon,