Grid snapping

Hello there, I am trying to make a building system and I have created a grid and can place a cube down and the other cubes can snap to the very first one, but they only snap to the first one, not to all the other ones. here is a picture for reference

As I said previously they can only snap to the first cube. And I don't know what I am missing here so I can make it snap to all the cubes.

I am going to post my 3 script files here:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class WallCollider : MonoBehaviour
 {
     Foundation foundationScript;
     Vector3 sizeOfFoundation;
 
     // Start is called before the first frame update
     void Start()
     {
         foundationScript = transform.parent.parent.GetComponent<Foundation>();
         //cube must have similiar length sides
         sizeOfFoundation = transform.parent.parent.GetComponent<Collider>().bounds.size;
     }
 
     // Update is called once per frame
     void Update()
     {
         
     }
 
     private void OnTriggerEnter(Collider other)
     {
         //create snapping ability
         if (BuildManager.isBuilding && other.tag == "Wall" && !other.GetComponent<Foundation>().isSnapped)
         {
             //so we can call foundation within this function
             Foundation foundation = other.GetComponent<Foundation>();
 
             //get mouse position
             foundation.isSnapped = true;
             foundation.mousePosX = Input.GetAxis("Mouse X");
             foundation.mousePosY = Input.GetAxis("Mouse Y");
 
 
 
 
 
             float sizeX = sizeOfFoundation.x;
             float sizeZ = sizeOfFoundation.z;
 
             switch(this.transform.tag)
             {
                 case "WestCollider":
                     other.transform.position = new Vector3(transform.parent.parent.position.x - sizeX, 0, transform.parent.position.z);
                     break;
                 case "EastCollider":
                     other.transform.position = new Vector3(transform.parent.parent.position.x + sizeX, 0, transform.parent.position.z);
                     break;
                 case "NorthCollider":
                     other.transform.position = new Vector3(transform.parent.parent.position.x, 0, transform.parent.position.z + sizeZ);
                     break;
                 case "SouthCollider":
                     other.transform.position = new Vector3(transform.parent.parent.position.x, 0, transform.parent.position.z - sizeZ);
                     break;
 
             }
         }
     }
 }
 

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Foundation : MonoBehaviour
 {
     public bool isPlaced;
     public bool isSnapped;
 
     public float mousePosX;
     public float mousePosY;
 
     // Update is called once per frame
     void Update()
     {
         //if wall is not yet placed
         //we need it to follow our mouse using raycast
         if (!isPlaced && !isSnapped)
         {
             //tell buildmanager that we are building
             BuildManager.isBuilding = true;
 
             Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
             RaycastHit hit;
             if (Physics.Raycast(ray,out hit))
             {
                 this.transform.position = new Vector3(hit.point.x, 0, hit.point.z);
             }
         }
 
         //placing wall down using left mouse button
         if (Input.GetMouseButtonDown(0))
         {
             isPlaced = true;
             BuildManager.isBuilding = false;
         }
 
 
         //release snapping ability for wall
         //mathf.abs is to check if old and new positions are different
         if (isSnapped && !isPlaced && Mathf.Abs(mousePosX - Input.GetAxis("Mouse X")) > 0.2f || Mathf.Abs(mousePosY - Input.GetAxis("Mouse Y")) > 0.2f)
         {
             isSnapped = false;
         }
     }
 }
 

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class BuildManager : MonoBehaviour
 {
     //default bool is false
     public static bool isBuilding;
     public GameObject wallPreFab;
 
     void Update()
     {
         if (Input.GetKeyDown(KeyCode.Alpha1) && !isBuilding)
         {
             //set true to prevent clones.
             isBuilding = true;
             //build a cube at coordinated 0,0,0 when key "1" is pressed
             Instantiate(wallPreFab, Vector3.zero, wallPreFab.transform.rotation);
         }
 
 
     }
 }
 

Anything helps really. Thank you for your time.