How to link 2 VirtualBox through VPN tunnel?

Question

virtual box

There is a host "A" (Win 2012 r2) and a remote host "B" (Win 7 x64). A tunnel is established between them via "Radmin VPN". Both hosts access the Internet through routers and have gray, dynamic IPs. Both hosts have VirtualBox 6.1 installed with guests: Win 7 on "A" and Win XP on "B".
You need to "drive" the guests into the established VPN tunnel "Radmin VPN" (LAN for guests through the tunnel), but isolate them from the hosts.
In the network settings of both VB set "bridge over Radmin adapter".
The IP data is as follows:
for "B": host 192.168.0.16 - looks through the router to the Internet
............. Radmin VPN adapter 26.155.151.44
............ .guest (XP) IP 26.155.151.77, DHCP 26.155.151.44, DNS 26.155.151.
for "A": host 192.168.0.157 - looks through the router to the Internet
.............adapter Radmin VPN 26.64.51.177
.............guest (Win8 .1) IP 26.155.151.110, DHCP 26.155.151.44, DNS 26.155.151.44, Gateway 26.155.151.44 (if automatically, it takes parameters from host "B") 2 identical adapters appear, all network machines (guests + hosts) appear in the explorer ), but for remote (when selected) it says "network path not found". If the adapter parameters are entered manually (with the values ​​of the local VPN adapter) - only the local host and the guest are in the explorer, and only the local host adapters are pinged from the guest, there is no connection with the remote OS.
.............guest (XP)/(Win7) IP 26.155.151.110, DHCP 26.155.151.44, DNS 26.155.151.44, Gateway 26.155.151.44 (if automatically, it takes parameters from the host " B") there is no communication with remote operating systems.

I tried several combinations of VB settings, tried to solve the issue with routing (I have a very difficult time with it, maybe I wrote incorrect routes). Been stuck for a few days now.
Please tell me how to solve this problem with the settings / routing?