  The entanglement of superpositions [Phys. Rev. Lett. 97, 100502 (2006)] is
generalized to the multipartite scenario: an upper bound to the multipartite
entanglement of a superposition is given in terms of the entanglement of the
superposed states and the superposition coefficients. This bound is proven to
be tight for a class of states composed by an arbitrary number of qubits. We
also extend the result to a large family of quantifiers which includes the
negativity, the robustness of entanglement, and the best separable
approximation measure.
