stretch handle accessed by parent cell

[jren]

First I create a PCell (name is "level 2") which contains a stretch
handle defined by rodAssignHandleToParameter(). Following in a cell
"level 1", I use "lever 2" as an instance. Then in the parent cell
"level 0", I use "level 1" as an instance.

My question is: how can I access that stretch handle owed by "level 2"
in "level 0" layout?
Any comment is welcome. Thanks in advance.

Jren