ignore any child colliders too?

How do physics ignore collisions to include all of any of an objects child colliders? I tried to plug in GetComponentsInChildren but I get errors with each attempt. With this code, it will atleast ignore colliders on first depth search

in Update(){

if(blah){
ignoreCollision(“Player”);
ignoreCollision(“Pet1”);

}
}

function ignoreCollision(tag: String) {
var objects = GameObject.FindGameObjectsWithTag(tag);

for (var o in objects) 
if (o.GetComponent(Collider) && o!= gameObject) {
Physics.IgnoreCollision(o.collider, collider);    

		}
	}

Iterate on each object’s transform to get their children. Recursively. Or make use of Layers.