Nishmas Kol Chai shouldn’t be included in Shabbos morning davnen. It doesn’t fit with the rest of psukei d’zimra because it’s not a passage/collection of verses from Tanakh, it’s long and boring, and there’s at least some argument that it was written by an apostate heretic (the man the Christians call St. Peter). All it does is bog things down between psukei d’zimra and shacharis.
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