I surely would like to see evidence of the existence of Lydia Cranston as well. No one seems to have it, and there is to my knowledge no information that Gov. Cranston ever had a daughter named Lydia. NEGS has no record. Naming her as the wife seems to have a life of its own, in that people copy down her name because so many have done so before.
It is sort of like the legend of Benjamin Harrington's royal roots in England--it is a very dubious connection but people still utilize it in their family treees as if it were proven.