I am Charlie Sepulveda and I am descended from the original Sepulvedas who came to California back in the late 1700s. My Great -Grandfather was Gregorio Sepulveda, and his father was Delores Sepulveda. I guess the family lived mostly in the Santa Ana area. My grandfather grew up in Yorba, and his father Gregorio is burried there in the Old Yorba cemetary, not too far away from Don Bernardo Yorba. Gregorio's father was Delores, and I'm not sure who his father was, it may have been Jose Delores whose father was Juan Jose. Juan Jose's father being Francisco Xavier.
I suggest, if you haven't already taking a look at a book called Saddleback Ancestors. It has my particular genealogy wrong, but it has stories of many of the families that lived in the Santa Ana Canyon area.
If any one has information, stories, pictures etc. that they'd like to share, please contact me at firstname.lastname@example.org