Tefillo Kehilchoso (ch. 11, fn. 284) and Shulchan Oruch (102:1) quote Tosephos Brochos 31b to say that one may sit beside someone praying the amidah if one is involved in prayer activity. He asserts that this includes even “aizehu mekomon” (part of the sacrifices section of morning prayers), “borchi nafshi” and “pirkei ovos” (said by some after the afternoon Shabbos service).
Can the “Kabbolas Shabbos” service composed by 16th century Kabbalists beginning with “Lechu neran’no” be considered the same as “aizehu mekomon” etc.?