How to: Child Account Set up to Enable Join Multiplayer Games

Before I start: sorry for my unclear English, I will try to explain my concern by editing the question, if necessary.

I have a private Microsoft account and a connected XBOX-account. I also have a child, which is part of my family in the Microsoft world.

Our purpose is that the child can play Minecraft with friends (multiplayer). He is using the Minecraft App for Android only.

I have read some instructions for family managing in microsoft and how to be able to join multiplayer games and finally about the option to use Minecraft as multiplayer game in a local network.

Now I have two questions:

1. How can I set up family settings in the XBOX management browser-app/tool? I cannot find the right place to do this, do I really need a native, mobile App in order to do this? The linked descriptions are not very telling in this regard.
   
2. Is this local network multiplay thing possible with Minecraft Android Apps at all?
   

:)