The present study investigates how 6 to 13 years old children appropriate their stepfamily/blended family (Malrieu & Malrieu, 1973; Malrieu, 1976) and how sibling relationships might influence that appropriation. Our analysis is based on the bioecological approach (Bronfenbrenner, 1996). Sibling relationships were examined using a semi-directive interview. The appropriation of the stepfamily was investigated on the basis of the drawing of the family, the Kidcope (Spirito, Stark and Williams, 1988), the Child Behavior Checklist (CBCL, Achenbach, 1991) and the “AUtoquestionnaire Qualité de vie-Enfant-Imagé” (AUQEI, Magnificat & Dazord, 1997). Results indicate that children make elective choices of their family members mainly on the basis of their biological relationships, the most important persons influencing their life and the quality of the relationship with their close circle. We shall emphasize that the most stressful factor generally evoked by children usually originates from the stepparent and his educational approach. Furthermore, the results show that social support appears as the most efficient strategy often used by the children. Generally, we noticed a satisfying socio-emotional adaptation and life quality of the sampled children. Mostly, the relationships among siblings are found as a resource within their stepfamily as long as those relationships are both sustained and supportive. Cross-correlated statistical analysis of the data showed significant influence of person characteristics (age, sex), family context (sibling characteristics, child custody) and time factors (elapsed time since separation, duration of the second union) on the appropriation of family.