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If person davens in a shul with other nusach. E.g. a nusach-ashkenaz-guy goes to a nusach-sefard-shul and in order not to get confused he wants to daven with the Tzibbur as much as possible.
What level of loyality to his own nusach should he keep?
Should he daven silently his own nusach Shmone Esre or can he rely on the shul's one?
Can he say psalm of the day together with the shul or/and shuld he repeat it after davening?