from single staff to piano staff

[mario]

Dear users,

I write because I don't know how to face this problem.

I have a single staff score, generated by my epiano in .mid and then 
converted in .ly through Musescore.

I would like to separate the staff in two staves (i.e. a PianoStaff). 

Is there a simple way to do that? 

You know, I was looking forward to something like \autochange - I don't 
remember the name, I also tried to do something like 

\new PianoStaff
{ \autochange { \relative c' {
    <c, ees a d g c>4 r <fis c' eis ais>~ <fis c' f aes bes>8~ <f b e g 
bes>~      | % 1
}}}

but it didn't break the chord in two staves.

Thank you very much in advance,

Mario.