www.wysiwygwebbuilder.com

Is it possible for a post form to add more upload fields if you need to send more than one attachment? If so, how can this be done?

Maybe this is useful?
http://www.wysiwygwebbuilder.com/fileuploader.html

Here is another option that may help.
I have a dynamic attachments extension.
https://shop.grahamscomputers.net/webshop.html

Click on view details then the demo link
Graham