Question How to apply an opposite torque on one rigidBody if the other was done with ForceMode.Acceleration ?

I have one RigidBody on which I apply an angular acceleration like this :
rb.addTorque(torque, forcemode.acceleration);
This rigidbody has a box collider.
I have another rigidbody with different mass and different collider (so different inertiaTensor), on which I would like to apply the exact opposite equivalent force like this :
oppositeRB.AddTorque(oppositeTorque, forcemode.force).
How can I do ?
Another way to see this problem is : how get the resultant torque of an angular acceleration of a rigidBody ?