Normality and shared values with multiple zeros

Let kk be a positive integer, a(≠0)a(≠0) and bb be two finite values. Let FF be a family of meromorphic functions defined in DD, all of whose zeros have multiplicity at least kk and f(k)(z)=bf(k)(z)=b when f(z)=0f(z)=0. If for each pair of functions ff and gg in FF, ff(k)ff(k) and gg(k)gg(k) share aa, then FF is normal in DD.