Can we update Old Nan's page? I believe the World Book finally confirmed that she was the wetnurse to William Stark and Lyanne Glover's son Brandon.
The Stark lineage tree says that this Brandon had no children, and the Brandon she was called in for died at 3 and thus didn't have children. He's also the only one who fits the rest of Bran's quote as Brandon can't have been an older or younger brother to Rickard as Rickard had no siblings. But he can be Edwyle's brother as Lyanne's child would be Edwyle's half brother. And Brandon son of Artos can't be the Brandon who Old Nan was summoned for as that Brandon had children and therefore clearly didn't die at 3.
So Old Nan has to have joined House Stark for William and Lyanne's son.