Using an App in a Different App in Background via PowerShell

We have a GUI (first GUI you can see in the video) that controls the machine, but we want to add some other functionalities to the machine. To do this, we made a different GUI (second GUI you can see in the picture) that adds these functionalities. To control the machine, we must use first GUI, but we want to use it in background. So, we need support from who can use PowerShell (or different things, but not like the AutoHotKey) to do this. We want to activate button from second GUI whenever we want and also use other functionalities of first GUI.