The normal famility of mermorphic functions

Let F be a family of mermorphic functions in a domain D, and let a,b,c be complex numbers, a ≠ b. If for each f∈ F, the zeros of f-c are of multiplicity ≥ k+1, and Ēf(k)(a) ⊂ Ēf(a), Ēf(k)(b) ⊂ Ēf(b), then F is normal in D.