f-related vector fields

Let M and N be manifolds and let f:M→N be a smooth map. A vector field X on M and a vector field Y on N are said to be f-related if

dfp(Xp)=Yf(p),∀p∈M.

This means that for every function

h:N→RXp[h∘f]=Yf(p)h.

Suppose that X is f-related to Z and Y is f-related to W. Show that [X,Y] is f-related to [Z,W].