The example file is attached on here (http://filesocial.com/1d4sbye).
When the file is opened, go to File -> Page Setup...
You can find another staff hidden.
(http://files.filesocial.com/thumbnails/610/1d5nnxk/f8b16cd15596ad142e700369314a93f4894bdb2d/091123-1.jpg)
Set the channel of three staves. They must be same.
(http://files.filesocial.com/thumbnails/610/1d5rkwz/b3f48b3fd01789018bbf61bfc5afa27708ba30f8/091123-2.jpg)
Pedal (sus) is a sort of Controller, so if you set the channels same, the piano sound will be pedal-ed.
Sesirine.