How to find out the host IP of a running MSTSC instance?

Question

Steps:

1. User run mstsc.exe instance; second instance; third and more;
2. I need to connect to my program, running on a remote host in all instances.
3. What is the way to get the address of the remote host in the mstsc.exe instance?

Knowledge:

I know, that mstsc set registry value when connected. Like this: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Terminal Server Client\Default

But

But this is a consequence, not a cause

hypothesis

1. Could it be that the host address is in the fixed memory address of mstsc?
2. Perhaps mstsc notifies about the start of a session and creates an event that can be intercepted?

P.S.

Any programming language

( For what? Our product is a UI helper for Windows users. And we want to make tooltips on remote UI)