int parentID = -262;
GameObject parentObj = null;
int sonID = 0;
GameObject sonObj = null;

// Find objects
var objects = RuntimeHelper.FindObjectsOfTypeAll<UnityEngine.GameObject>();
foreach(GameObject obj in objects)
{   
    if (obj.GetInstanceID() == parentID){
 parentObj = obj;
        Log(parentObj);
 }
    if (obj.GetInstanceID() == sonID){
 sonObj = obj;
        Log(sonObj);
 }
}

if (parentObj != null && sonObj != null){
    sonObj.transform.SetParent(parentObj.transform);
}
else{
    if (parentObj == null) Log("Couldn't find parent");
    if (sonObj == null) Log("Couldn't find son");
}