[spoiler="Writing songs for the new voices and instrument"]
Unlike traditional instruments the new instruments and the voices have a very specific range. If you write a note out of its range it will simply "silent" the note since it cannot play. The ranges are the following:
Piano: o1c ~ o7c
Violin: o1e ~ o4b
Cello: o1c ~ o3a+
Vocal (Male): o1f ~ o4c+
Vocal (Female): o1c ~ o3a
Choir (Male): o1d ~ o3a+
Choir (Female): o1g ~ o4c
That means if you play out of line of the assigned notes, it will simply be silent.
Now what does it means? Let's take the Female Phantom Chorus. It can only go from the first octave "g" to the fourth octave C... it means it will not play the fifth octave nor will it play things like lower than octave note G.
The easiest way for one to make a "quick fix" to songs is to add a o1 or o2 infront of their MML scroll such as below:
o1+76v15l8>b+bag4d4.a1b+bag4f#4gg4.gf#dc-d4e4
While that may make the song singable, a true writer will want to manipulate the octaves and notes in order to accommodate the change.
However, lowering it an octave will just make it sound softer or sharper, so song coded with sensitive octaves will need to be re-written carefully.
[/spoiler]