I should read papers about Remedello C. I've only a generalist book upon Bronze Age in Europe, a compilation by J. BRIARD.
in it I red Remedello was a well organized and "shining" group, of Chalcolithic culture influenced in old time by BBs; surely some ties with Rhone Cultures. The Unetice influences came later. It recalls me a metric survey about Eneolithic Mediterranean Europe by CHARLES (old: 1950-60) saying about Italy the Chalcotihic there took 2 forms: a so called "mediterranean" one and a "northern" one, mixed everywhere but with two opposite poles of dominence, so their names. Charles saw a 'balkanic-mediterranean' element coming in Italy by land through North, from Balkans. I suppose the "mediterranean chalco" came from Egea without knowing more. Remedello so is not typical Bronze? and we know from papers upon Hungary auDNA of Chalco and even Bronze that the "steppic" mediated auDNA was weak then, we saw rather a so called WHG DNA rising and seemingly only in Bronze - it's true our ancient DNA is still scarce enough for making to selfconfident conclusions.
concerning Y-I2a1-M26 I red it was found today by example in ancient maritime megalithic regions; by the way the Sardinian M26 - founder effect or not - is by definition in a maritime position - the same concerning the eastern shores of Adriatic. Maybe the last SNPs of M26 were born by West-Balkans people firstly acculturated by people of the Central Balkan Copper settlements? just a track, because maybe we 'll discover other more numerous Y-I-M26 in other locations changing hypothesis; either I-M26 is a peculiar well defined source of I2a1 and linked to megalithism (a) and first knowledge of metals without "industrialization", b) and only some contacts with regions of true metallurgists), or M26 was largely distributed but was acculturated at last by first Copper people from East on their road...