2 SOPHOS XG + 2 LAN INTERFACES ROUTING PROBLEMS

Question

Hi, and sorry for my poor english. 
 I have 2 Sophos XG 18 connected to LAN with the same Switches. The first Sophos (Intel Hardware) have 2 WAN + 1 LAN (172.16.1.10/12) + 1 WIFI (192.168.100.1/24) the second sophos (vmware) have 2 WAN + 2 LAN (100.64.0.1/16 and 172.16.1.9/12 + 1 WIFI (with some AP55 + 5 SSIDs) + 4 VPN SSL with 3 remote offices. The new Sophos XG works fine, can I see all networks, VPNs to LAN1, VPNs to WAN, some WIFIs SSIDs to VPNs and LAN1... now I have connected the two Sophos with a IPSec Site-to-Site Tunnel, and obiusly, the LAN2 in the Second Sophos are set to None. 
 I'm trying and read all posts in this community to set the LAN2 Interface to IP 172.16.1.9/12 to remove the IPSec Tunnel, 1.- Add new Zone (LAN2), 2.- Assign LAN2 Zone to interface PORT B, 3.- Assign Static IP to PORT B (172.16.1.9), 4.- Save changes... I see the Network 2 (172.16.0.0/12) from Sophos, but not from VPNs and WIFIs, from first Sophos can't see the Network 1 (172.16.0.0/16)... i'm writing Firewall rules: source LAN, LAN2, VPN destination LAN, LAN2, VPN Accept, we write a Sophos 1 route to see the Sophos 2 network: destination 100.64.0.0/16 Gateway 172.16.1.9 interface (none) metric 0... and nothing seems work, only the IPSec Tunnel. 
 The offices has to access to some resources in the 172.16.0.0/12 network, and this network has to access to some resources of 100.64.0.0/16 network. 
 Anyone can help me please? 
 Thx for advance

HardikR · Answer

As I understood your network diagram, 
 Your traffic flow would be, 
 From Lan zone: 
 LAN(100.64.0.0/16) --->PortA(100.64.0.1/16) companyA XG --->PortB(LAN2-172.16.0.1/12)----> switch ---- (172.16.0.0/12) 
 From WIFI Zone: 
 WIFI---> (Port E) companyA XG---> PortB(LAN2-172.16.0.1/12)----> switch ---- (172.16.0.0/12) 
 From VPN Zone: 
 SSL VPN---> companyA XG---> PortB(LAN2-172.16.0.1/12)---- switch ---- (172.16.0.0/12) 
 
 On companyA XG 
 firewall rule should look like: 
 Source zone: LAN, WIFI,VPN 
 Destination zone : LAN2 
 Source and destination network can be set to Any or as per your requirement. 
 Along with this, try to create linked NAT rule with source translation as MASQ. 
 With source translation as MASQ, you would be able to access company B network(172.16.0.0/12) 
 Considering PortB(LAN2) of companyA is set to 172.16.0.1/12) 
 As per your initial description, you have set correct firewall rule, however linked NAT rule might not bet configured due to which reply packets are going to default gateway(company B XG) and probably getting dropped there.