How to make rigidbodies on each side of a cube fall towards the cube? [multiple gravity / addForce]

I have a world cube (as opposed to a sphere), and on each of the six sides i have rigidbodies that need to fall towards it's relative side/ground. ConstantForce's Force parameter won't work because the world cube will need to rotate, and when that rotates, all the rigidbodies global rotation axis also changes. The Relative Force parameter won't work either because the rigidbodies themselves can also rotate independently, so their local rotation axis can change.

So i figure some type of script that runs AddForce and adjusts the vector based on position and rotation of the rigidbody in relation to it's side would be the solution. I've posted in the forums about it (forum post) but haven't received any replies.

My current solution works but i feel there must be a better way. You can find my current unity project at my Github with the scene set up with the cubes, but i'll also post the script here. The rigidbody must be child to the collider surface/ground/side it should fall down towards.

rigidbody using System.Collections; using System.Collections.Generic; using UnityEngine;

 [RequireComponent(typeof(Rigidbody))]
 public class gravityBody : MonoBehaviour {
 
     public float gravity = -10f;
     Rigidbody rb;
 
     void Start () {
 
         rb = GetComponent<Rigidbody> ();
         rb.useGravity = false;
         
     }
 
     void FixedUpdate () {
     
         rb.AddForce(rb.transform.parent.up * gravity);
 
         //rb.AddRelativeTorque(new Vector3(0f,-0.25f,0f));
 
     }
 }

thank you.