DottieD'Luscia said: "I had no idea he was responsible for the orchestrations for Music and the Mirror."
According to David Chase, HW was responsible for the entire dance arrangement. Reposting David's social media post:
If I mention "The Cassie Dance', what names come to mind?
Michael Bennett, who choreographed it...?
Donna McKechnie, who was the first in a long line of brilliant women who performed it...?
How about the brilliant dance arranger and orchestrator Harold Wheeler who wrote it...?
Wait, you say, I thought Marvin Hamlisch wrote 'The Music and the Mirror' ?! Well, he did (along with lyricist Ed Kleban) but that dance music was by Harold, starting with that slow, sexy sax solo...
When A Chorus Line started rehearsals at the Public, Hamlisch took a stab at writing the dance music himself. (He was an experienced dance arranger in his own right - check out "Henry, Sweet Henry", "Minnie's Boys" and "Seesaw").
It didn't work.
Michael Bennett and Harold Wheeler weren't on speaking terms - they had done "Promises, Promises" together and had had a falling out. But Michael knew that he needed Harold to make the Cassie dance work. Drummer Bobby Thomas invited them each out independently to have a drink, then left the bar when they both showed up. Michael and Harold settled their differences, and the rest is history.
Remember, choreography does not exist without music.