regarding transfer of lease hold property

my aunt (younger sister to my mother) unmarried, died at the aged 90+ had executed a registered will in favour of my real sister regarding aunt's lease hold property. Now the respective housing authority asking to deposit requisite transfer fee ( un-earned increase) since it is transfer outside blood relation whereas "within blood relation/ inheritance legal heirs-non testamentary", it is exempted. under the circumstances, what's the advice, please