Iframe form data transfer

I’m new to iframes and ajax but here is what I am trying to do.

I have a form on my parent page where the user is finding a file to upload. I also have an invisible iframe with the dame form field by a different name.

Parent Input:

<input type="file" id="ghost" name="ghost" onChange="javascript: ghost_change();">

ifame “invis” form:

<form name="upload" action="imageupload.php" method="post" enctype="multipart/form-data">
<input type="file" id="image" name="image">

I need the data that is in the parent input field to be transfered to the iframe field onchange.

Can it be done, and how?