In that case, Use the third nic to totally replace firewall B. You will
have a line from switch B to Firewall A Nic 3. It will be configured like
the LAN of Firewall B. You will need rulls for that Nic as well.
But routing will be solved.
IC, so that will be the last resort then. Is it possible that we use 2
firewalls so that we can keep the rules for Company B in FW B and rules for
company A in PC A?
I figure doing three NICs to replace firewall B would also require moving
all the rules from FW B to Firewall A. Because some users are allowed to
access internet, but some are not.