switching from grand staff to one stave
Take a look at Canon top and Canon bottom attached. You'll see that the director wants to take vv 1,3,4 in unison but vv 2,5 in parts. Therefore I've laid out the top part in one stave and the bottom part in grand staff.
You'll see that I've cancelled the title information in the bottom part so in principle I can just cut and paste. I don't even need to cut and paste physically; I can use the tool paint.net to combine the top and the bottom in a new picture. I made the top and the bottom compatible by choosing the same value of sp.
Is there a solution in Muse score proper without resorting to paint.net? We need to be able to start a layout in one stave and then at the end of a system change to grand staff for the rest of the piece.