Disklavier

I have a new Yamaha DGC1M4 Mark IV piano and I am trying to find out 
what other manufacturer's discs will play in my system. Are QRS, 
Pianodisc, Pianomation, and other non-Yamaha discs compatible with the 
Mark IV? Does anyone have a list of non-yamaha compatible discs? 
Freddy at Yamaha suggested I post this message on this site. The main 
reason that I am asking is that we purchased the Disklavier for my 
daughter who is an aspiring musical theater/singer and we want her to 
be able to rehearse at home with pre-recorded piano accompaniment. She 
will be starring in Annie Get Your Gun and Thoroughly Modern Millie in 
a few months and I am having a hard time finding these song files (I 
could not find them in any of the Yamaha discs). I did find some of 
the Annie Get Your Gun songs on a QRS CD (Broadway Musicals I QRS 
Catalog #400401) but there is a disclaimer that says that "QRS Music 
CD's produced after 1/1/05 are designed expressly for the use with QRS 
Pianomation Systems, and we do not guarantee compatibility with other 
brands ..." Can anyone out there give us some giudance? Thanks!