Yogi, Philip Barry wrote the theatre play The Philaddelphia Story specifically for Katherine Hepburn to star in. She also financed the staging of the play, taking a share of the profits instead of a salary. Howard Hughes bought the film rights as a gift for her and then have them to her, She sold the rights to Louis B Mayer but with the provision that she had a right of veto over producer, director, screenwriter, and cast. Besides being an outstanding actress she was a shrewd businesswoman.
The play was adapted into the musical High Society years later by John Patrick as screenwriter for the film and Cole Porter for the songs. That was in 1956.
Years later that film was adapted back into a stage musical by Arthur Kopt (the writing) and the music used the music and songs from the film but was adapted by Susan Birkenhead.
So you've seen all three versions