Re: Making a volume/partition available to all users
No need to reformat.
Firstly you need to make an fstab entry for it
Secondly I imagine you would need to create a new group, add the three users to the group, and then recursively modify permissions on the drive to your liking.
Here's a simple write up to help you understand permissions better, and to give you an idea of what you are doing.
"You can't expect to hold supreme executive power just because some watery tart lobbed a sword at you"
"Don't let your mind wander -- it's too little to be let out alone."