Two gateways on two different Windows, how to make client machines work through both at once?

Question

Windows

Sorry for the chaotic and noob question
Available:
gateway for accessing the Internet on Windows 2003 sp3 + Kerio Control
gateway for accessing the intra and no organization network on windows xp
, some machines need only an intranet (PC4 in the figure), some only need the Internet (PC2 and PC1 in the figure)
A group of machines appeared (PC3 in the figure) that need access to both. Can you suggest how this can be done?
From the Internet, only a browser is needed. For example: by registering the Kerio gateway with access to 10.10.XX
, transfer to 192.168.1.40, but then how to do reverse routing so that packets from the intranet reach the recipient if there are several such PCs?
Here is a simplified network diagram:

Answer 1

Use one gateway - it's easier to manage access.
And on kerio, just add a route to 10/8 through 1.40.

Answer 2

And I would redo the entire network.
I would remove Kerio. Would lift one general gateway on all networks. Would configure VLAN on it. Divided networks into VLANs.
Basically, that's how I'm organized. It is easier to build routes inside one gateway and manage a firewall.
And so, your network is too complicated .. I would say not optimal.
In your situation, raise another gateway that looks at all networks and build routes on it.
In general, read about VLAN , and life will become easier.