The support provided to families with disabled children is exclusively focused on the disabled child or his/her parents. Although current trends emphasize the need to work with the family as a system, minor siblings are usually at the margin. My article paid attention to joint education, which is the situation when the disabled child attends the same school that his/her "healthy" sibling does. The study was aimed to find out whether the teachers at such schools know that the children in their class have a disabled sibling at the same school, how they treat him/her with respect to the relations with classmates, what responsibilities is the child assigned by the teachers and the parents in connection with the help with the education of the disabled sibling. The research done through a self-structured questionnaire took place at 32 schools where disabled children and their siblings attend inclusive education. The study result was sad. The detailed analysis of the findings showed that most teachers do not know that the child in their class is the sibling of a disabled child going to the same school. That means that they never spoke with them about that topic, they never expressed understanding of his/her difficult life situation, they did not help in case of conflicts with the classmates, they did not support him/her.