Francisco Xavier Sepulveda y Garcia was born circa 1742 at the Villa de Sinaloa, Mexico. His parents were Juan Jose Sepulveda and Josefa Garcia. (They did not make the move to Alta California.)
In 1762, Francisco Xavier married Maria Candelaria de Redondo (aka Arredondo).
In 1781, Francisco enlisted with Captain Fernando de Rivera y Moncada, and with wife and 6 children, accompanied an expedition into Alta California. (They entered California in August.)
Francisco died at the Pueblo de Los Angles and was buried at Mission San Gabriel Cemetery on 26 January 1788.
That's pretty much all I know. :)