Mazel Tov on moed katan - Moed home stretch! Chagiga 2

(in lieu of Reb Avi who seems to be without an Internet connection during Chol Hamoed!)

in "the rosh yeshiva remembers" (Rav Bergmans book about Rav Schach tranalated by atscrol) page 266 he bring azoy:
Rav Schach in a periodical publication argues that there is a special mitzva to bring שלמי שמחה in addition to tothe mitzv of eating as part of simchas y"t. the chazon Ish argued with him sharply and held that if a Jew brings such an offering as a Mitzva he would transgress בל תוסיף. The chazon Ish held that there is a mitzah to eat meat of a kurban and if he has no other Kurban he would bring a שלמים. Later rav shach was showed that the אמרי ברוך also holds like him. The issue is the rambam in beg of Hilchos Chagiga.
Later Rav shach was asked from a Gemara Menachos 90b where the ברייתא lists the obligation that come with y"t as Olos R'iya and Shalmei Chagiga but does not mention Shalmei Simcha. Raz scach agreed that his was proof to the chazon ish (see more aci ezri hilchos chagga). The story in the book was brought with more details to show the humilty of Rav Schach, see there.