Visually editing components created with CreateDefaultSubobject

I’m pretty new to unreal and I’m trying to understand the interaction between actors and components which are written in C++ and actors and components in the blueprint designer.

I would like to create a custom component in C++ which creates some child components automatically, so when you add the component to an actor, the child components are automatically attached to the component tree as children.
I would like these child components to be rendered in the designer. I’d like to be able to manipulate their relative position using gizmos, I’d like to be able to set their properties using the details panel.
I want to know that the custom component will always have a reference to these child components and that they are always added to the actor together.

Is it possible to achieve this in Unreal Engine?

I have tried achieving this in the custom component’s constructor using CreateDefaultSubobject and SetupAttachment but while the components can be seen in the blueprint scene, they are not listed in the tree structure and I cannot manipulate them.

What you are looking for is a “Scenegraph”. For now Unreal Engine does not support well such paradigm.

But they are working on it, with the new scenegraph system in Fortnite and UEFN (Scene Graph | Unreal Editor for Fortnite Documentation | Epic Developer Community). Hopefully, this will come in UE 5 in a future version.