Securing group communications in resource constrained, infrastructure-less environments such as Mobile Ad Hoc Networks (MANETs) has become one of the most challenging research directions in the areas of wireless network security. MANETs are emerging as the desired environment for an increasing number of commercial and military applications, addressing also an increasing number of users. Security on the other hand, is an indispensable requirement of modern life for such applications. The inherent limitations of MANETs impose major difficulties in establishing a suitable secure group communications framework. This is even more so for the operation of Key Agreement (KA), under which all parties contribute equally to the group key. The logical design of efficient KA protocols has been the main focus of the related research. Such a consideration however, gives only a partial account on the actual performance of a KA protocol in a multi-hop network as protocols have been evaluated only in terms of the key related messaging in isolation from network functions that interact with the logical scheme (i.e. routing). In recent work, we contributed towards the latter by efficiently extending a number of Diffie-Hellman group KA protocols in wireless multi hop ad hoc networks. In this work, we are extending a scheme that was left out in our previous work: Hypercube. Through analysis and simulations we demonstrate the superiority of the new, enriched H-Cube that takes into account the underlying routing by the use of a topologically aware communications schedule.