The corpus of Judeo-Spanish ballads presents a unique case study of stability and change in oral tradition. On the one hand it is a living testimony to the jews' preservation of the Spanish Romance tradition after their expulsion from Spain in 1942; on the other, by absorbing since then so many new stylistic features, it has evolved into a genuine repertoire quite distinct from that of the late Medieval Spanish Romancero, its ancestral counterpart. Consequently, melodic variants of individual Sephardic romances often show a diversity that calls for a fresh approach towards what is implied by the notion of "variant", and a more flexible methodology for the comperative study of variants. Such a fresh approach and flexible methodology are presented in the present article. Ludwig Wittgenstein's conception of family resemblances is applied to related versions of a Sephardic Romancero. Four absolute parameters (formal structure, modality, melodic type, and metric organization) and three relative ones (melodic similarity, pitch axes, and rhythmic similarity) are outlined. By encoding each variant according to these parameters and examining its relationship to other variants of the same romance, the dominant parameters in the oral transmission of a particular romance are established.