Security concerns with accessing Intranet URL link of an NPM in the NOC view

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 ?