When arriving late to synagogue on the festival of Shemini Atzeret, after the congregation has recited the Moussaf prayer, one should recite the prayer for rain during even during the morning Shacharit prayer, since the congregation has already announced the rain, unless his intention [in prayer] rests on the fact that the public did not recite it during Shacharit. In this case he must do likewise – not recite it during Shacharit but rather during Moussaf. This question may also arise on the first day of Passover… Whether on Passover or on Shemini Atzeret, the ruling is the same - according to what the congregation does: If one arrives late to synagogue, after the congregation has recited Moussaf, one must recite it during the preceding Shacharit prayer, as did the congregation during Moussaf, meaning that on Passover one must mention dew and on Shemini Atzeret one must mention rain.