The paper uses the most general version of a Dixit–Stiglitz economy and the concept of oligopolistic equilibrium, defined in previous work, with firms maximizing profits in prices and quantities under a market share and a market size constraint. The purpose here is to take even more advantage of separability so as to partition the oligopolistic sector into groups. Weak separability simplifies quantity conjectures and homothetic separability simplifies price conjectures. Oligopolistic equilibria can in addition be approximated by introducing group expenditure conjectures. Finally, the way different groups interact within the same industry is illustrated within the same framework.