How do i get the parent of an actor ?

I want to make an array with all children actors of an actor, immediate and not immediate as well.

Children means attach right ? can i just use this one ?

Or do i have to use this one?..

There is this which is probably more what you need

AActor* MyActor;
TArray<AActor*> ChildActors;
MyActor->GetAllChildActors( ChildActors, true)

default is ture for include descendants FYI