malsup jquery form beforeSerialize passing file data

malsup jquery form beforeSerialize passing file data

Hi,
I am using malsup jquery form for uploading images for asp.net.
I have three FileUpload in my webform. Ids are FileUpload1, FileUpload2 and FileUpload3.
In my server side I wish to parse the file as  below:
httpPostedFile = HttpContext.Current.Request.Files["UploadedImage"];

If my fileUpload control name/id is UploadedImage, it is working fine. But I have three controls , so I gave them three different Id.
-------------
In my previous code I used form Data. It wa possible :
eg: var data = new FormData();
var files = $("#<%=FileUpload1.ClientID%>").get(0).files;
data.append("UploadedImage", files[0]);
---

As this code do not work in some versions of IE, I changed my uploading code to malsup form.
So Is there any option to append form data before submitting?
I have seen this for normal input fields eg: textfield, but could not find it for fileUpload element.
Please advice.