Louilla Lewallen? Whose is she?

1900 US Federal Census lists Anna Lewallen (b May 1834) living with her son James (b Jan 1871) and five-year-old granddaughter Gertrude (b. June 1894). Anna reports that she is the mother of 13 children, 6 of whom are living. Somehow I have Louilla Lewallen (no dates) among fourteen children of Anna and Walter Davis Lewallen. I don't think Louilla belongs but I don't know to whom she belongs, and I don't want to erase her altogether until I can place her with her family.