Thank you - It's as I feared.
I thought I would explain why I need this facility and hope that will persuade the developers to prioritise the suggestion.
I use jDownloads for a Town Council's website. It's a bilingual website so downloads need to be shown on both versions of the site. Various documents (e.g. agendas, minutes, audits, budgets etc) are uploaded by the Council's staff for the public to download in accordance with the Council's open government policy. I was hoping that the non-technical staff would not need backend access. The system is fine for documents when there are separate versions in the 2 languages however if the document is either bilingual or only available in one language (e.g. an external audit) then I can create a download in one language, uploading the document and then when I create the corresponding download in the other language I can simply Select the file from the other download. The council staff cannot do this from the frontend which means that they will either have to load the same document twice or will need backend access. Neither is ideal.