Reply To: Blender 2.91 Official Release is here!
Experimenting with “Rigid Body Compound Shapes”:
A circle has been broken into separate objects consisting each of a single edge which have been set up as “Active Rigid Body” objects using “Convex Hull” as “Collision Shape” without any “Collision Margin” . These “Circle Piece Objects” – after having set their “Object Origins” to “Geometry” – have been parented to a “Cube” which has been set up as “Active Rigid Body” object using “Compound Parent” as “Collision Shape” without any “Collision Margin”. The “Circle Piece Objects” now stop exactly at the surface of the “Cone” which has been set up as “Passive Rigid Body” object.
So, “Compound Parent” in Blender 2.91 works with an arbitrary number of “Children” objects as “Collision Shapes” which are (as their “Parent” object) “Active Rigid Body” objects. Before Blender 2.91 you could only parent an object to one object set up as “Active Rigid Body” object which served as “Collision object”. The “Child” object was no “Rigid Body” object.
File is here.