Entanglement based quantum communications and quantum networks are considered as fundamental resources to address the demand of secure communications. In this context, the architecture known as quantum relay plays a crucial role as it allows linking together independent communication channels each spanned by a pair of entangled photons. In particular, this scheme is particularly interesting for long instance applications where the bad effect of propagation losses and detection imperfections can be reduced by dividing a long link into shorter subsections and connecting then via entanglement teleportation [1].