Board Thread:Warhammer 40k General Discussion/@comment-58.178.141.62-20140405080514/@comment-2093048-20140408164504

some far fetched hints are made at other chapters being based on traitor legions ( sons of antaeus f.e. though that hint is small) and  even if not saved, IOM had f.e. 70 loyal death guard, a couple of iron warriors and others.

Most people think Warsmith Dantioch (leader of a bunch of loyalist iron warriors that ended up on Maccrage and became beloved by Roboute and the Ultramarines there) became the Silver Skulls. It's explicitly stated that the Skulls only claim to be Ultramarine second founder successors with no proof yet work closely with the Ultramarines, Dantioch wore a mask that looks like a silver skull, and lots of people reading the silver skull novels thought they were Iron Warrior loyalists from their personalities even before Dantioch came out (the Silver Skull's penchant for Prognostication explicitly comes from their home planet, not their gene seed, and thus isn't a factor in what primarch they come from)

But yea, there's also at least 70 loyalist Death Guard too. Though it'd be kinda hard to get a chapter from that small amount I think, unlike Dantioch or Arvidae's groups (which are much bigger).