I not completely sure of how you have things setup, but here is a script that when the parent receives a collision, the children are made visible:
#pragma strict
function OnCollisionEnter() {
var renderers = transform.GetComponentsInChildren(Renderer);
for (var rend : Renderer in renderers) {
rend.enabled = true;
}
}
Also note you may want to remove or disable the colliders on the sub-objects depending on your use. Even though the renderers are disabled, the colliders will still be active unless you remove or disable them. Also note that ‘GetComponentsInChildren()’ is a bit misnamed since it also returns the parent you used in calling the function.