In Firewall Rules add a rule to the "All Applications" category. You'll need one rule for each samba server. You'll also need to have a fixed IP address for each server (unless someone can tell me how to specify a range of addresses).
Suppose your systems are on the 192.168.x.x subnet and 192.168.1.15 is a samba server. In the rule specify:
1) Apply this rule to all applications
2) Permisson: allow
3) Network type: Home/Office
4) Protocol: 6: TCP
5) Direction: Both
6) Click "show advanced settings"
7) Custom Local Address: off
8) Custom Remote Address: on
9) IP: 192.168.1.15
10) Port(s): 137, 138, 139, 445
11) Click "save"
