Most musicals are owned by either Tams Witmark, Music Theater International, or Rodgers and Hammerstein.
If the musical you’re looking for is listed by any of these three companies, the orchestration will be listed on their websites.
David Daniels’ book “Orchestral Music” is a wonderful resource for orchestral repertoire. I have the 3rd and 4th editions. It’s really interesting reading if you love orchestral music.
Neither of the two works that you’ve mentioned have a harp part listed.
If Kalmus carries the music you can get a lot of information here (http://www.kalmus-music.com/). Clinton Nieweg’s editions are also listed with full instrumentation information.
The problem with Musicals is that many have been reorchestrated for a smaller ensemble and frequently do not include harp. They will use instead a keyboard with a “harp” button.
And these days they frequently use a keyboard with a “whole orchestra” button. Ability to actually play a keyboard is optional as the notes are already programmed in.