Adding more field at attachment category

Thanks for the good words about MLA and for your question.

There is nothing in the current MLA version that would help you add additional fields to the attachment_category, attachment_tag or other taxonomies. There is nothing in the WordPress database design that supports adding fields/columns to the database tables that support the taxonomies.

I regret that the answer is not more positive. I am marking this topic resolved simply because there is nothing in the MLA plugin that can satisfy your requirements. Thank you for your understanding and your interest in the plugin.