How to share an existing mount point with Samba app

I’m trying to add a second Samba share but am seeing some unexpected folder behavior that I do not understand.

I’ve mounted my media folder as an open share at /mnt/NAS/FreedomBox/shares/open_share and it’s working fine. I’d like to add a home share on the same disk, so created one with the Samba app.

I expected the home share to be created here
/mnt/NAS/FreedomBox/shares/homes

But instead it’s been created here
/mnt/NAS/FreedomBox/shares/open_share/FreedomBox/shares/homes
i.e. under the existing open share. That’s a whole new directory tree!

I’m assuming it’s possible to have shares of different types on the same disk. If that’s the case, then what am I doing wrong here?