like one of the youthful groups leaders of Latin America and Spain. The album included hits like No seas tan cruel, Besos de ceniza, Mírame (Cuestión de tiempo), Si no es ahora, Con todos menos conmigo, Rompecabezas, Mágico amor and Ya estaba escrito. In that same year, Timbiriche interprets the main theme of the telenovela Quinceañera, that was carried out by Thalía and the actress Adela Noriega. In December of that same year, the group is invited to participate in the Christmas album Esta navidad, next to another artists. Timbiriche interprets the song ¡Ay del Chiquirritín!. In that same month, Mariana Garza, another of the founding members of the group, announces her departure from the group to enter as a television actress. It is Mariana herself who chooses for her replacement Edith Márquez, another young girl who was also part of Greases cast. In addition, Edith already was well-known for her participation in the TV sitcom Papá soltero. Edith lived a difficult process of adaptation when arriving at the group. Adult Band (1988-1991) The double album Timbiriche VIII & IX was released on 7 May 1988. The record was produced as a double album, as producers did not decide to choose the repertoire of songs that would include in the new album. At the time, the double discs were a novelty in Latin America and few artists were encouraged to produce them. The album (which was also released for sale separately) included the hit singles Tú y yo somos uno mismo, Ámame hasta con los dientes, Acelerar, Yo no se si es amor, Me estoy volviendo loca, Junto a tí, Máscaras, Pasos and Tú me vuelves loco. This period is considered as the zenith in the trajectory of the group and gives another step in its evolution, positioning itself as a young adult band. In November 1988, Alix, another of the founders, decides to leave the group to prepare her solo career. After a series of auditions, in February 1989 her place is occupied by Bibi Gaytán, who ends next to the rest of the members the tour corresponding to the double album. In February 1989 goes out for sale the first compilation album of the group titled Los Clásicos de Timbiriche. The album contains a compilation of the group's greatest hits, accompanied by the Symphony Orchestra of Mexico City, and was recorded in the Sala Netzahualcoyotl of Mexico City.