[Samba] SAMBA - how to restrict read and write

[fasil km]

Hi,
First of all let me thank you all for such a good support :)

I am trying to create a share that can be accessed by few users. In that, 2
users alone should have write permission.
please find below my smb.conf file

[share]
comment = armand_share
path = /armand_share
writable = no
read only = no
browseable = yes
writelist = @sharewrite
valid users = carlo,isidro,philip,faisal,jojo,retish

I have system users and samba users created with the same names.

#ls -l /
drwxrwxr-x    3 armand sharewrite  4096 Sep 28 12:36 armand_share

armand and carlo are the members of the group sharewrite.
Now when the user carlo creates anything inside the share, it is not
accessible (or viewed) by any other users including armand.
I need both armand and carlo be able to write to the share and rest of the
users be able to view.

One more thing I noticed,
If a user, e.g testuser, access the share with the credentials of armand or
carlo and write to the share, the permission is set to testuser.testuser
why is that so?

-- 
Thanks & Regards,
Fasil
Mob: +966 55 8567449