I have a suggestion, provided you would be willing to instead host the files on the SME Server. I don't pretend to be a guru so someone tell me if I'm way off the mark. What I suggest below is based on my own kludging around with SME. My solution involves Ibays and a knowledge of WinSCP and symlinks. Personally, I think this might be a little more elegant and easier to maintain.
Setup a usergroup including username1 thru username6
Create ibays, for example;
ibay "readwrite", where usergroup has read and write access
ibay "readonly", where admin has write access and usergroup only read access
Using WinSCP, login to the server as root (using SCP protocol, not SFTP).
Browse to /home/e-smith/files/ibays/readonly
Right-click on the "files" folder, choose Properties, and change owner to "username1". You can do the same for the ibay "readwrite", but I don't think its necessary.
Now the tedious part. Within WinSCP, goto each user accounts personal folder;
i.e. /home/e-smith/files/users/username1/home
Within each, create a simlink to each ibay you wish to share. For example, right-click within home folder, choose New > Link, name it "readwrite" and point it to /home/e-smith/files/ibays/readwrite/files. I'll point out that the owner of the symlink is "root", therefore the user cannot accidently delete it.
AFAIK, from the XP users point-of-view, this should appear the same as if you had created all the mounted folders as you described. Username1 will have full read-write access to all the files and the file sharing task is on the server where it belongs.
I hope this helps.
