Is the rotation of an Object on the Y axis identical to another object?

Question

Unity

Hello, I really don’t know how to make the brain boil anymore. In general, there are two empty objects, one I rotate in all axes, and there is also a second empty object that should rotate along the identical Y axis of the first object, only along Y.
That is, ob1 has rotated 10 degrees and ob2 also rotates 10 degrees. I already tried QuaternionY but xs either I'm cancer or I didn't build it correctly. In general, who can help plz)

Answer 1

as an option, I can suggest in the update of the child object to subtract the x and y axis of rotation of the parent