Mootools: How to add items to an existing Fx.Sort instance

Question

I've got a problem with Mootools Fx.Sort.

<ul id="list">
   <li>One</li>
   <li>Two</li>
</ul>

Javascript:

mySort = new Fx.Sort($$('ul#list>li'));

I can add more elements to the list:

$('list').adopt(new Element('li', { text: 'Three' }));

But the run-time created list elements, obviously, are not considered by Fx.Sort instance and they cannot be sorted with the others.

Is there a way to add them to the existing Fx.Sort? Or the only thing is to replace mySort with a new instance every time I add an element at run-time?