addAt(child, index, silent) → {DisplayObject}
Adds an existing object to this group. The child is added to the group at the location specified by the index value, this allows you to control child ordering. If Group.enableBody is set, then a physics body will be created on the object, so long as one does not already exist. If Group.inputEnableChildren is set, then an Input Handler will be created on the object, so long as one does not already exist.
Parameters
Name Type Argument Default Descr