Considering the specific difficulties and characteristics that result from Autism Spectrum Disorder (ASD) itself, a family takes on a new role and faces various demands and changes. The family plays a significant role in providing support to a member with ASD and, alongside the redistribution of roles in families, siblings often take on roles that ease the burden on parents. Therefore, the aim of this paper is to show the contribution of autism to a family, as well as different experiences of family support from the perspective of the siblings of adults with ASD. This qualitative research was carried out as part of the project "Families in Croatia impacted by Autism Spectrum Disorder" in collaboration with associate professor Alexander Jensen from Brigham Young University, based in Provo, Utah in the United States of America. The research participants were selected using the non-probabilistic convenience sampling method, and 5 participants from the Zagreb and Split area took part in the research. The sample included adult siblings of adults with ASD. The collected data was transcribed and analyzed using thematic analysis as defined by Braun and Clarke (2006). The resulting themes and subthemes include positive and negative contributions of ASD to the whole family, sisters and brothers; the experience of providing support to siblings; their perception of support provided by parents and extended family; emotional and financial support; the support of non-governmental organizations and social care; and the problem of providing support in the future. The obtained results show the complexity of ASD's contribution to the whole family but also to each individual member from the perspective of sisters and brothers. Furthermore, they provide a deeper insight into the experience of providing support to a family member with ASD, which includes assuming pivotal roles and responsibilities of all family members.