We are trying to achieve this scenario. its simple setup but security is our biggest concern. Facility A is the prime location and can not risk compromising? can a NOC view of Facility B risk access to Facility A?

Are their any security concerns if adding Intranet URL link of a remote NPM to the main NPM in the NOC view ?
there is concern if Facility-B intranet NPM can become a backdoor for attackers. can URL access to an intranet server become backdoor. if so then How to stop it. can it interfere with the main Facility A NPM?
how can we secure this Intranet NPM communication and user access ?