I wouldn't recommend doing that. UD adds additional things to the share configuration such as the recycle bin if that plugin is installed, and some entries to deal with case sensitive names, and Mac OS interoperability. It's also very easy to mess up samba shares when making manual entries.
A cleaner approach would be to partition the disk with multiple partitions on a PC. When you put the disk back in Unraid, you then set each partition mount point for the share name you want, and you'll have multiple shares on one disk with all the extra things UD handles. Down side is each share is limited by the partition size for the shares.
If you need more share control than that, use Unraid shares.