How to organize sub-apps system in node?

Question

Node.js

I'm new to node and I want to understand one thing - how to make a kind of constructor - where does the main application scatter over servers with additional applications without reloading?
Those. I have servers A, B and C, each server has its own functionality (different applications, for example, some coworking with sockets) and server A as an arbitrator has a user database i.e. requesting the main page of example.com, we will see links to applications there example.com/app1,example.com/app2,example.com/app2 - respectively for each server The
question is - how to make it possible to connect / disconnect new servers G, D, E... etc. with new functionality, but still the same common user base
Please tell me in which direction to dig