Is it all possible to redirect a PDF's url from one provider to another?

We have a document toolkit.pdf that, when we transitioned from our old platform to Sitefinity was added into multiple different subsites' document providers. This has created an issue where, when the document is updated, it is only updated in the subsite/provider for the section responsible for maintaining it, so the version on the others is not.

I would like to set it up so that we can redirect all of the other versions (/docs-sf/other-libraries/documents/toolkit.pdf) to the up to date one (/docs-sf/service-library/documents/toolkit.pdf), but I am running into problems.

First Attempt: I unpublished and deleted one of the outdated ones and added it's url (/docs-sf/other-library/documents/toolkit.pdf) to the additional urls to file for the correct version but the old URL 404'd. so I then tried adding it as (/other-library/documents/toolkit.pdf), but it still 404'd so I suspect the "additional" urls are forced to begin with /docs-sf/service-library/ (in other words my adding the additional url to file of /other-library/documents/toolkit.pdf makes the actual additional url /docs-sf/service-library/ /other-library/documents/toolkit.pdf which obviously is not correct).

So I went back to the drawing board.

Second Attempt: Set-up up page redirects to allow for the .pdf extension and created a redirect page for it under the top level and set it to point to the correct version of the pdf, then gave the page the url of the old one (/docs-sf/other-library/documents/toolkit.pdf). But when I tried to publish, it came back with an error message saying "The name 'docs-sf' is reserved by the system. Please choose a different name."

So, is there ANY way whatsoever to make it so a document or document url (formerly) from one provider/library can redirect to a document in a different provider/library? Apparently a number of things link to one of the outdated documents and it is on a subsite that only admin can access so the users who actually do the document updates cannot upload it there and it is causing problems.