Merman and Martin were actually good friends -- so much so that they did several concerts over the years together.
"Something about Ethel doing a play and Mary watching it opening night. Before the first act was over Mary had either her agent or a producer/lawyer find out who owned the rights so she could do the tour of that production."
The only role of Ethel's that Martin toured was Annie in ANNIE GET YOUR GUN, but I never heard that story before. The story sounds apocryphal since Martin knew full well going in that Irving Berlin wrote the show and that her good friends Richard Rodgers and Oscar Hammerstein produced the show. I don't know who the hell the agent or whoever would have been running off to contact in the middle of the first act.
"What a story........ everything but the bloodhounds snappin' at her rear end." -- Birdie
[http://margochanning.broadwayworld.com/]
"The Devil Be Hittin' Me" -- Whitney