I'm not sure, but I thought the Dwarves of the Blue Mountains were mostly the folk of Nogrod and Belegost, supplemented by some (but not all) of those of Durin's folk who had survived the Sack of Erebor, with the rest just wandering around in Middle-Earth. That is however, pure conjecture, based on what seems to make the most sense to me.

_________________
"... Telchar wrought it in the deeps of time."
-On Andùril, The Lord of the Rings