Auto detect items from a different network

Hi!
I already saw a similiar topic but the host had an ip address for both networks there.
I have my openhab host in my private network (192.168.20.0/24). This network is connect to my fathers one (192.168.178.0/24) via a wireguard installation (10.0.20.0/24). The hosts that are connecting the networks is a vm on my end and a raspi2 on my fathers one.
New items are mostly added in the network from my father. My OH3 vm doesn’t directly know about that network. Traffic is getting routed over the wireguard vpn.
Is there any way to tell OH to look up new devices in the 192.168.178.0/24 network?

Traffic example:
192.168.20.205 (OH3)
192.168.20.1 (router 1)
192.168.20.204 (wireguard)
192.168.178.25 (wireguard)
192.168.178.1 (router 2)
192.168.178.X (target host)