The playbill credited Lew Kessler with having staged "When We're Home on the Range," "There's a Happy Land in the Sky," and "By the Mississinewa."
Several months into the run, Ethel Merman became convinced that Paula Laurence, playing her sister, was trying to upstage her during their show-stopping second-act duet, "By the Mississinewah." According to the account in Brian Kellow's Ethel Merman: A Life, Laurence kept stealing bits of Merman's own business during the number. Merman complained to the stage manager, and he presumably conveyed the message to Laurence. When Merman's complaints did not stop Laurence's behavior, Merman demanded that she be fired. Laurence would later insist that she was not fired but quit. (All of this is according to Kellow's book.) On June 1, 1944, Betty Bruce took over the role.
Bruce, trained as a ballet dancer, originally had major dancing (much of it tap) to do in the show in her original role (Betty-Jean). She also seems to have understudied Betty Garrett, who played a character named Mary-Frances and understudied Merman. When Garrett missed several performances in April 1943, Bruce played Garrett's role while also performing her regular dance routines. When it was first announced that Bruce would replace Laurence, it was at first said that she would also continue to play her own role, but when the time came, another cast member, Mavis Mims, was promoted to take over Bruce's original role (and her dancing assignments).
Eventually, Garrett got her chance to temporarily leave her regular role and go on for Merman. This occurred in October 1943. She played the role for five performances. Merman, though suffering from a bad cold and laryngitis, called Garrett before her first performance to encourage her. As Garrett later recounted it (quoted in Ethel Merman: A Life), Merman asked her, "How ya doin', kid?" Garrett told Merman how nervous she was, and Merman responded, "Listen, kid, if they could do it better than you, they'd be on the stage and you'd be in the audience." Garrett told the New York Times (in an article titled "Pity the Poor Understudy," January 2, 1944) that Merman sent her a ring to congratulate her on the success she had in those performances.