sortable handle problem

sortable handle problem


i have a div(parent) which is a container for sortable items. i would
like to give the handle property of sortable method in jquery ui only
to the grandchildren not to either of children or great
grandchildren.
here is my html:
<div id="parent" class="parent" >
<div id="child" class="child">
<div id="grand_child_1" class="grandchild" > </div>
<div id="great_grand_child_1"
class="greatgrandchild" > </div>
<div id="great_grand_child_2"
class="greatgrandchild" > </div>
.
.
.
<div id="great_grand_child_n"
class="greatgrandchild" > </div>
<div id="grand_child_2" class="grandchild" > </div>
<div id="great_grand_child_1"
class="greatgrandchild" > </div>
<div id="great_grand_child_2"
class="greatgrandchild" > </div>
.
.
.
<div id="great_grand_child_n"
class="greatgrandchild" > </div>
<div id="grand_child_3" class="grandchild" > </div>
.
.
.
.
<div id="grand_child_n" class="grandchild"> </div>
</div>
</div>
How can i achieve this using jquery?
Thanks in advance....
regards,
krish