I believe it's safe to say that Paul Riser was an outstanding force behind many of the instrumental arrangements for Motown especially for those strings on "My Girl" and for his backing arrangement of "Papa Was a Rolling Stone." For the latter, he was awarded a Grammy.

Later on, he also worked with R Kelly and arranged the Grammy award winning song, "I Believe I Can Fly." The partial discography lists some amazing work that he has done.

Through Wikipedia I am learning that he played, uncredited, trombone on some of the early Motown recordings. It says that he considered the Diana Ross track of "Ain't No Mountain High Enough" to be his favorite arrangement.

Another interesting tidbit was that he was a co-writer for "What Becomes of the Brokenhearted." Are there other Motown songs out there that you know of that were written/co-written by him?