Hello,
I wanted to ask how to detect collisions from child components.
I have Component A (some Scene component) and Component B (some static mesh component) as child (A and B are near each other, they are not in same location, they are is some distance) .
I want to use AddLocalRotation/AddRelativeRotation on Component A and detect HitResult from child (in this case Component B).
Is this possible?
Hey @LUKASZJB!
You can use the On Component Hit node 
To place it in your Event Graph, you can simply select your static mesh component from the Components window on the top left, and while having it selected, right click on an empty space in your Event Graph, type in “on component hit” on the menu that pops up, and hit enter! Or you can also head to the Details window on the right side while having your static mesh component selected, scroll all the way down, and under the Events section, hit the plus (+) icon next to the On Component Hit option.
Hope this helps! 
Yes, this is what I though about but maybe there is better solution.
Lets say I would like to have something more complex like “Mechanical Arm” where we have Some Base + Sphere Joint + Arm + Sphere Joint + Arm.
How should this kind of stuff be created?
If you’re gonna make each of those sections static mesh components, you detect hits on the components. If that’s gonna be an SKM, you detect hits on the bones.