Is it permissible to spend the money received from the orphan society on household expenses for my younger sisters (under 13 years old), given that my deceased father's salary has stopped and we have no income?

The funds allocated for orphans are a right of the younger sisters, and if these funds exceed their needs, then the maintenance of the needy sisters becomes obligatory from them. This is because the maintenance of needy siblings is obligatory upon those among them who are well-off. There is no condition of reaching puberty or being sane for the one upon whom maintenance is obligatory. However, if the sisters become self-sufficient, they are not permitted to take anything from those funds.