... if I want to leave her abroad with my sister in the summer, and return to Ukraine myself. Will it be enough to have a power of attorney from me alone, that my sister is responsible for my child's life during the child's stay abroad.
... if I want to leave her abroad with my sister in the summer, and return to Ukraine myself. Will it be enough to have a power of attorney from me alone, that my sister is responsible for my child's life during the child's stay abroad.
The father's permission is not required, because the child is already located and lives abroad. You should warn him that you are leaving the child with his sister for a while. This can be confirmed by your power of attorney.