Reply To: Solo accompaniment different keys
Great question!
I would place the key signature for each part after each marginal hand sign (and after a space) as we would if there were a key change or a time signature change. I have had some Bartok piano pieces in which the two hands are in different keys. This is how I indicated those different signatures. The time signature would remain in the music heading with the tempo indication (if present), but without a key attached to it. You can always cover your bases by adding a sentence about the irregularity on the Transcriber's Notes page or right before the music to give the reader a heads-up.
Hope that helps!
Kathleen