Name of the software
Why we should include this into the repository, i.e. what does it do that the alternatives do not?
It allows to combine several mount points into a single one. I didn't find another option to do this. The code hasn't been changed in a while but it still seems to be functional. Debian also includes it (https://packages.debian.org/search?keywords=mhddfs).
Is it open source?
If it is open source, please provide a link to the most up to date, versioned source tarball/zipfile. master.zip links will not be accepted.
In case it helps, I have a working package.yml for my personal use here: https://gitlab.com/cherrypicker/solus-packages/tree/master/mhddfs