Access on child's trigger in parent script

Hello,

I have a empty gameobject (A as example) - there is a script on it.
I have a second empty gameobject (B). B is a child of A and has a trigger.
I want to have access on this trigger in my script of the parent. The script must not have a script, only a “Box Collider” as trigger.

Is that possible and how?

Hm, I put a rigidbody on the parent and turn “Is Kinematic” on. This works. Have anybody else an idea?