Somteimes teh rights holders surrender to popular demand if they can.
So many people were adding "I Have Confidence"and "Something good" to stage productions of TSOM that for a while theywere offered at an additional fee.
The 1998 Broadway production re-wrote the show to be more like the film, putting "My Favorite Things" in the Thuderstorm scene and bumping "Lonely Goatherd" to the concert scene (where it worked quite well, sounding as it does like folk song.)
But still, many groups try lifing some of the dialogue from the movie and the R&H organization stopped one regional from doing this simply because the screenplay is controlled by 20th Century Fox...and not R&H.
In cases where the movie impoves upon the show, naturally people want to take advantage of those strengths, but when you buy the rights to do S fo M, or GREASE you are NOT buying the rights to stage the film: You are buying the rights to do the stage play and the contract specifies it must be done as writen.
Cast albums are NOT "soundtracks."
Live theatre does not use a "soundtrack." If it did, it wouldn't be live theatre!
I host a weekly one-hour radio program featuring cast album selections as well as songs by cabaret, jazz and theatre artists. The program, FRONT ROW CENTRE is heard Sundays 9 to 10 am and also Saturdays from 8 to 9 am (eastern times) on www.proudfm.com