How to ensure newly created files on network drive are read-write for everyone?

How to ensure newly created files on network drive are read-write for everyone? ------------------------------------------------------------------------ **In brief.** When a user creates a document/file on the network server volume at /users/shared/"M C"/, the document ends up being editable only for the user who created it and Read-Only for everyone else. I need it be editable for everyone. **Specifics** With the client user Mac account 'AAA', a file is created on the networked drive in a folder called 'M C' in /users/shared. **The permissions for that newly created file will be Read-Write only for user 'AAA' and undesirably Read Only for the 2 other users listed: 'Staff' and 'Everyone'. I want it to be 'Read-Write' for everyone** (or preferably for only certain users but I'll settle for everyone right now) Similarly, if a Mac user 'BBB', in the same way as 'AAA', connects to the server and creates a file, it will be Read-Write for 'BBB' but Read-Only for all other users. I need all newly created and edited files to be editable by all users. The files in that directory need be shared. **Environment** The client Mac runs macOS 13 (Ventura). The server runs macOS 12 (Monterey) but may upgrade it soon to macOS 15 (Sequoia). User 'AAA' connects to server using their own (sharing only) Mac account on that server. The folder 'M C' is shared: The folder 'M C' has been added to the list at System Settings > Sharing > File Sharing > Shared Folders. Its 'Get Info' window has 'Shared' ticked. The folder 'M C' has Read-Write permissions listed for the users 'AAA', 'BBB', 'Staff', and 'Everyone'. This is shown in both 'Get Info' window and sharing control panel. **What I've tried already** I applied Read-Write permissions to the folder 'M C' for all users but that doesn't help. The contents are unaffected (as expected). I applied Read-Write permissions to the folder 'M C' for all users and all contents but that doesn't help. Existing files will get Read-Write permissions for all users but thereafter, newly created files will be Read-Write only for 'AAA'. Where possible, I tried making these changes in both the Finder's 'Get Info' window, and the System Settings > Sharing control panel. In the System Settings > Sharing control panel, in desperation, for the folder 'M C', I even secondary-clicked it > Advanced Options > ticked 'Allow guest users', but that did not help. (Other options there are not ticked) I have tried placing the folder in other locations (eg, server's home folder), but it makes no difference and I figure /users/shared/ ought be the safest option for this to work. Can anyone help with this issue?