Monitoring PostgreSQL with multiple instances

Hi, I’m configuring the Checkmk agent so that it can monitor the PostgreSQL database with several instances, but I have a doubt when I do it.

1º Can you create an agent without having to put in the explicit rule the host that I want to add in the monitoring rule? This is because I want to create a single agent and install it on each of the machines that I create a database with different instances.

2º I have created a single file with the user and password of PostgreSQL, called .pgpass, can I use this file for all the instances or should I create a file for each one of the instances inside its directory?

3º How can I see each of the separate instances? Another thing I see is that all the information comes out together and you can hardly differentiate which instance it is.

Greetings and thank you very much