Need help setting up permissions on multiple user accounts

Question

Hi, here's what I'm trying to accomplish...
I run a recording studio and would like to have a personal account that I work from and an engineer account that myself and other artists work from. From the second account I created I will open an audio project in cubase (which is possible because the file can be read), then I will try to save it and of course it says I cannot edit the file. I can change the permissions on the file (or all the files in the directory) which will then give me access, however once I create a new file under this user account I am unable to save it back in my main account. I would like an option for a directory to be able to be read and written to by both users automatically regardless of where the file was originally created. I've tried setting up shared folders to work this way, but to no avail, once a file is created the option to read/write the file is automatically set to only the creator not any other accounts. Please let me know what I am missing, I've searched endlessly for this, but came up with no results.
Thank You!
Jared

Answer 1

If you're interested in more suggestions, here's mine. The disk image idea will work, but it makes backup more complicated. Create a new folder in some existing public folder such as /Users/Shared to hold the projects. Decide whether you want to allow read/write access to all users, or just to some. If only some, create a new group in the Accounts preference pane and add the users to it.
Download the application Sandbox. Launch it in your administrator account. Click the "Inspect folder" button and navigate to the folder you just created. There should be one line in the window representing an entry in the access control list (ACL). Edit the entry by clicking the pencil icon. Make the entry type "Allow access." Make the group "staff" or the group you just created. Enable all the access permissions you want, and make sure everything is inherited. Save the entry and quit Sandbox. Now copy -- don't move -- the projects into the folder.