Then why didn't this change affect ALL *kw as it did in those few Celtic and Italic languages? The answer is that, regardless of when and where this change occurred in Greek dialects, it was a different, more restrictive sound change, and one possibly triggered by different phonological phenomena. After all, it occurred only before [a] and [o]. This is not the "fashion" of P-Celtic nor P-Italic languages, but a different process leading to similar results only in some words, but not in others (see "tis", "lukos" >>>> not, "pis", "lupus"). I'm not saying this change did not happen, and I'm glad you informed us when it happened, before Attic Greek (here I was just repeating what Papadimitriou had taught us some messages back in this same topic) and in fact still in late Homeric periods. But, still, I repeat: it's not the same change that happened in Celtic and Italic languages only much later (during the early Iron Age they were still Proto-Celtic and Proto-Italic, all of them with *kw), and all these changes are at least 1,500 years too late to have anything to do with Yamna, even in its latest stages.