Access network of VPN from different VPN

[Ecuvaro]

Hello,
i am setting up remote access to some devices using VPN.
i need to have some of them "isolated" so some people can only access that group, while a lot of them should only be accessible by administrators.
my thoughts were to put those groups into their own VPN servers and have a admin access server that can see all the other networks.
while setting up a new server and adding the network of the other server to it in "local ipv4 networks" i noticed that i don't get access to the devices connected to that though.
help would be appreciated if i need to do some more configs to access the other servers or if there is a different solution to my problem.
Thanks in advance