[Samba] require membership to two groups

[Christ Schlacta]

I have some shares on a media server that are considdered "Local, 
offline content", namely they should be accessible if the rest of the 
network is down, and each system has it's own group of users who are 
allowed to maintain it.  the media servers in the livingroom are only 
for my wife and I, but each person can modify the one in their own 
bedroom and noone elses bedroom.  Furthermore, the users must be members 
of the group "Music" to be allowed to modify music, and the group 
"Videos" to be allowed to modify videos.  currently my setup looks like 
this for rebirth:

[videos]
         comment = Rebirth local Videos
         path = /media/local/videos
         write list = @rebirth
         force group = videos
         create mask = 0664
         force create mode = 0664
         directory mask = 0775
         force directory mode = 0775

[music]
         comment = Rebirth local Music
         path = /media/local/music
         write list = @rebirth
         force group = music
         create mask = 0664
         force create mode = 0664
         directory mask = 0775
         force directory mode = 0775

but my fear is that someone not in the music group will still be able to 
write to the shares.  is there a way to make it explicitly require BOTH 
groups to allow writing?