Piano sounds rather than chorus oo and ah

I would like to change the choral oos and ahs to piano sound. This would be piano single line staff, with separate playback channels, and staff names remaining as Soprano, Alto, etc. I want this for 2- and 4-staff layouts, and, I may add more staves as needed.

Every time I try, though, I’m getting a grand staff. What am I doing wrong?

If you use, say, HALion Sonic, go to Play, open HS, then change all the oh–ah to Piano, loading it in the corresponding channel.

I changed a solo Lead (ah) to piano:

Lead to Piano.dorico (594.4 KB)

P.s: Sorry, in my example I used the big HALion (it’s my preferred), but it’s exactly the same with HS. I’ll add the HS version:
Lead to Piano HS.dorico (557.8 KB)

Indeed, the way to do this is purely in Play mode, rather than doing it by changing anything to do with the instruments themselves.

I shared the steps to do this very thing in this post: