I usually just create different database files and share them with a Dropbox link, having two different files with two different random keys. I'm using version 2.09.
I have a "personal.kdbx" database that has all my personal stuff and a "company-name.kdbx". I usually use the "key file" option to open the databases since it's easier to the people I share with to copy it to an old USB drive and say "this drive is needed to open the passwords in the file, DO NOT lose this flash drive".
I don't know if this approach is a good one to your scenario, I think you're looking for some kind of "groups permissions" in a single *.kdbx file. I don't think this is possible. I haven't seen this option on the KeePass website or in the documentation.