Jaclyn Smith is only in the close-ups of the ballet scenes, however two different women are in the long shots doing grand jete, assemble and pas de deux. They are credited at the end of the show, and on the IMDB page under "Other Crew" as Betsy Erickson and Diana Weber. They were both principal dancers with the San Francisco Ballet.
Jaclyn Smith does her own ballet dancing with the San Francisco Ballet.