GMS 2 How to "parent" physical objects to another? (Box2D)


Hi there,

I'm new to Game Maker Studio 2, even though I used Game Maker 7 and 8 a lot back in the day. However I'm completely new to physics, and I started looking at tutorials for basic physics simulation. Then tried different types of joints. So far so good. What I can't find information about though, is how to attach many objects together, or possibly to some kind of parent object, so that if the parent moves or rotates, everything follows? Do I have to create many joints by hand?

Here's what I'm trying to do:
It's a fixed screen room, no scrolling. Think kind of like Elevator Action, side-view of a building, platforming and gunning happens on every floor using physics, except the whole building can tilt to one side, thus making objects slide because of gravity. I need a way to rotate the building and have all the floor/wall objects and their collision shapes follow.

Any pointer is appreciated, thanks!