Unity search all chidren of parent object
using System.Collections.Generic;
private List<GameObject> listOfChildren;
private void GetChildRecursive(GameObject obj){
if (null == obj)
return;
foreach (Transform child in obj.transform){
if (null == child)
continue;
//child.gameobject contains the current child you can do whatever you want like add it to an array
listOfChildren.Add(child.gameObject);
GetChildRecursive(child.gameObject);
}
}