Can you give zakat to your unmarried sister if your father is earning?

Yes, you can give zakat to your unmarried sister even if your father is earning. Zakat is meant to assist those in financial need, and if your sister requires support, it is permissible to help her with your zakat funds. The obligation of zakat is to aid those who are less fortunate, regardless of the financial status of immediate family members. However, it's always good to consider the overall financial situation of the family when making such decisions.