On Shmini Atzeres I went out to the lobby when yizkor was being said and I noticed that one of my daughters was still saying pesukei d’zimra because she came late (my daughters unfortunately think Shabbos and Sunday are sleep-in days). I realized that when we re-enter shul the gabai will announce that we should start saying mashiv ha’ruach u’morid hageshem in our tefilas musaf, but my daughter would hear that announcement before her tefilas shacharis. Question: having heard mashiv ha'ruach announced, must she now add mashiv ha’ruach in her tefilas shacharis?
I had somewhere in the neighborhood of five minutes at best to figure out what to tell her to do, and the Mishna Berura does not discuss this case. So all you Rabbi-wanna-be’s – what would you say? I’ll give you a chance to comment before I give away what I told her on the spot, how I would formulate the issue or question, and what I think in hindsight the right answer is. The best solution is, of course, to get to davening on time and not have such problems, but such would make life too easy.