How to give access to some network services, provided that both offices work in other people's networks?

Question

VPN

Good afternoon!
Organization "Horns and Hooves", works in the network of another organization "Hooves", connected to their AD (both are subordinate to the same higher institution). It is not yet clear whether this will always be the case or a transitional period (reorganization).
The organization "Horns and Hooves" has a branch that also works in a foreign network of the organization "Left" .. generally not related to our parent organization.

Is it possible to link a branch with the organization "Horns and Hooves" without interfering with the settings of the network of donor organizations, how to do this?
If you need more information, I will provide. Thank you!

Answer 1

Raise VPN on VPS and connect offices to it