You seem to fall into the same trap each time, perhaps you need to rethink your expectations of how instances work. When I started with Babylon.js I also had certain expectations of how thing would behave, which were wrong. Just a question of re-focusing.
If you re-read the post where you found this you will see that this is not a reference to instances not being applied to children but to a separate issue of hiding both a parent and its children. In DK’s reply you should note that he is answering these two separate questions but in reverse order to the way they were asked.
Do not let any of my comments stop you asking questions as this is often the only way to get clarity. Think about what it is you now know that you did not know before and be glad you are learning.