There was no "Elinor" among the children of Henry Custis and Joane Whittington.
It is not possible that *she* went to Massachusetts while her husband went to Maryland and the rest of her family went to Eastern Shore Virginia.
One must be VERY VERY CAREFUL not to confuse any stray Darseys/Darcys/D'Arcys with the Dorsey descendants of Edward Dorsey, Boatwright. The Dorseys have been prove by Y-DNA evidence *not* to be D'Arcys, and all current indications are that they originated in Ireland (as native Irish, *not* Norman colonizers).