Uploading Multiple Attachments From Front-End With A Description

I am working on a WordPress site that has a custom front-end submission form for adding in a post of content type, ‘sketchpad’. The form has a section that allows you to upload multiple images with a description field which is going to be used as an alt tag. What is an easy way for me to upload multiple attachments with accompanying descriptions from the front-end?

How to manage attachment relationships for specific posts in WP 3.5+

In WordPress 3.5, media management has changed entirely. Also, relating attachments to specific posts is (I believe) basically only being done for backward compatibility. Therefore, after uploading attachments from within the media modal to a post of any post type, it establishes a relationship where the post ID is the parent of the attachment ID, like it’s been for a long time.