Okay, a little while ago, someone (SiliconDream, I think), made a reference to the Old Races faced by the Trow being percieved to come from "outside" the known world, and hence not be children of Wyrd. However, the same seems to be applicable of the Dwarves:
"Twelve generations had his people roamed the above world. Now they stood on the cusp of retreating back into their stone carved chambers, not to see the light of the sun for many long years. If ever."
Note the words 'roamed the above world'- implying that there was a time when Dwarves existed, but did not roam the above world- burrowing forth from the earth, much in the style of some of the Old Races. If we are to accept that the Dwarves are children of Wyrd, it would seem reasonable to assume, then, that the Old Races were also children of Wyrd, especially in light of the Trow flavour text running something to the effect of "all who oppose us will come to ruin at our hands, be they human, Sileh'heh, Calliach, Oghre, or other children of Wyrd..."
