Is there a way to make a hyperlink to a file get recognized as a movie?

[crambles]

It sounds like you have a flat folder structure.  As in all your movies are simply in the "Movies" folder.  Ideally, each movie should be in their own folder within the library folder.  This is primarily so you can have things like extras and trailers together with the movie.

Once you've done that, THEN you can symlink the Home Alone folder in the other library you want it in.  Jellyfin should follow symlinks for folders.

Ah this is a good idea! Thanks!