TO ADD OR NOT TO ADD "DE" IN A SURNAME?

Message from Yolanda Medina-Perez windrocklili@...

HOW DO RANCHOS MEMBERS HANDLE THIS, IT HAS BECOME A CONFUSING DILEMA
FOR ME. I PUT IN ROBALCAVA AND FOR HIS DAUGHTER I FIND HER AS DE
ROBALCAVA....I LATER CAN'T FIND HER UNTIL I REMEMBER TO LOOK
UNDER "DE". I NEED SOME GUIDANCE FROM YOU EXPERIENCED GENEALOGISTS.
MIXED-UP IN EL PASO YOLANDA MEDINA PEREZ