(Kerio) How to see a LAN computer through a VPN connection?

Question

Computer networks

A server with Kerio Control
3 interfaces is installed: Lan, Internet, VPN
It distributes IP addresses: for Lan clients: 10.10.0.1 255.255.255.0
And for VPN clients: 10.15.0.1 255.255.255.0
10.15.0.1 and 10.10.0.1 is Kerio.
In Lan there was a PC with IP: 10.10.0.15, it was moved to another location and connected via VPN.
He received IP: 10.15.0.20
In the traffic rules, he indicated that when accessing from the network 10.15.0.1 255.255.255.0 to the address 10.10.0.15, there is a broadcast (MAP) to 10.15.0.20.
As a result, VPN clients understand where to knock.
I prescribe the rule:
from the network 10.10.0.1 255.255.255.0 to the address 10.10.0.15 there is a broadcast (MAP) to 10.15.0.20.
But here's the catch, no one except Kerio from LAN clients knows about 10.15.0.20
And in fact, all computers from any subnet do not see computers on another subnet.
How to set visibility?
UPD:
It works only if there are rules on Kerio, and if you specify route on the machine in the LAN.
If one of the two is missing: no pings.
Question: what is missing, so as not to run to each car and not prescribe a route?