the Giovanni had their patriarch get eaten and were forcibly folded into a new sect with the Cappadocians, Harbingers of Skulls, Samedi and even the Nagaraja, who aren't even a Cappadocian descended bloodline (the authors insist on calling it a clan, but this eclectic bunch would actually be a sect).
Objection! All mentioned bloodlines, save for the Nagaraja, are Cappadocians, so it indeed is a Clan. Now, there has been precious little detail regarding Nagaraja origins, except for hints that a group of Indian death Mages discovered their own version of the Ritual of Usurpation some time before the Tremere did theirs. The Tremere used Tzimisce vitae in their ritual (making them a Tzimisce bloodline, technically). There is ZERO information what vitae did the Nagaraja use. Given their penchant for death, though, it isn't a far stretch to assume they cooperated with a Cappadocian, making their presence in Clan Hecata very logical.
And the Lasombra? All the important ones (including the Archbishop of fucking Milan) shacked up with the Camarilla
Giangaleazzo was the first to do so, even back in V20.