Two staff system editing issues

I started work on a two staff system with snare drum part on staff 1 and drum set part on staff 2. I went out of town after saving the file. When returning, I found the snare drum part on staff 1 was uneditable (can delete measures but it will not allow reconstruction of deleted measures). The Snare Drum part on Staff 1 is complete for the piece, but Staff 2 needs completion. Staff 2 is also uneditable, so I cannot finish the piece. I went to 'Instruments' and found that somehow, both Snare Drum and Drum Set are assigned Staff 1. When I started the process, Drum Set was on Staff 2. It will not allow any Staff additions beside Staff 1 nor allow reassignment of Drum Set to Staff 2. I cannot bring up the Drum Set Palette either. What am I missing?