In this paper, new operators for fusing logical knowledge-bases (Kbs) are proposed. They are defined in such a way that they can handle Kbs that must be interpreted under forms of the closed- world assumption. Such assumptions implicitly augment the Kbs with some additional information that could not be deduced using the standard logical deductive apparatus. More precisely, we extend previous recent works about the logical fusion of knowledge to handle such Kbs. We focus on the model-theoretic definition of fusion operators to show their limits. In particular, the basic logical concept of model appears too coarse-grained. We solve this problem and propose new operators that cover a whole family of fusion approaches in the presence of variants of the closed-world assumption.