Though I remain admittedly rather confused on the tricky issue of relation versus being, it appears to lie at the crux of what my project is attempting to get hold of. Again this is where Badiou's usage of Category Theory in Logics of Worlds is crucial. Badiou seeks to deny relation (for him deployed to describe the logic of appearance, or, as he puts it, of being there) an ontological primacy: relation comes after its terms, and has no bearing upon them. As Hallward describes it in Subject to Truth:
"Categorial elements are nothing but relations of self-identity, expressed by a function of appearing or measure of existential intensity. If relation does not create difference, we might say, it is because it creates identity itself" (Subject to Truth pp.314-5).
In summary then, Badiou employs two different regimes: being/the ontological/set theory and appearing/logic/category theory. Within the latter domain, whilst at first it might appear as if relationality is key, in fact this is constrained to self-relationality, with relations between elements being strictly a secondary derived property of this. Perhaps I am confusing things here, but it certainly seems that in this regard Badiou comes very close to Deleuze, in that relations between elements are always secondary to the relations of those elements to themselves (cf: difference-in-itself) This comes close to Deleuze's position (as
Schoolboyerrors puts it):
"... the differential relation between bodies/forces/etc, in which the two terms in the relation are brought together, their degree of power measured against one another, and given specific qualities on the basis of this. (like, in the determination of forces two forces come into contact and the one that is of a greater quantity of force is designated active, the other reactive...)."

Instead of “quantity of force” we might read “existential intensity” or in CT terms, degree of self identity. Hallward's final word on this matter however is positively intriguing, critiquing both an ontological viewpoint determined solely by elements, with no regard to relations (ie- set theory) and an onto-logy/logic of appearing determined entirely by (self) relations and ignoring all elements. vis:
"...the alternative to either of these singular positions [is] that both elements and relations can be accounted for only together, as co-implied in a single process that maintains the elementary integrity of what is related precisely insofar as it is related." (Subject to Truth p.315).
In a sense this posits a genuinely relational theory and hints in the direction of Hallward's own project on relationality. A thorough going investigation of this question is essential in order to fully grasp an intersubjective theory of groups. Further, an interesting parallel presents itself. It is almost as if Badiou, in writing Logics of Worlds, is following the path of Sartre once more. Sartre's philosphical arc between his early work such as Transcendence of the Ego and Being and Nothingness and the later Critique of Dialectical Reason is one of attempting to build into his earlier, ultimately non-relational theory some degree of relationality, in this case admitting the social into a previously highly individualistic system. This attempt was not entirely succesful, given that he denies any positive role for sociality outside of the group-in-fusion, and even within it the relation is always between individuals, who remain entirely primary. Badiou begins from a different position of course, with his daring wager that the discourse of being-qua-being is set theory. His latest work attempts to introduce relationality into the system, but does so only on the basis of a primacy being given to self-identity or existential intensity within the domain of the logic of appearances. Further the relation between his two domains, between relation and being, remains somewhat obscure. In a similar fashion to his forebare, it appears that though Badiou gestures towards the direction in which he wishes to travel, he appears unable to complete the journey.