  A simple "trick" is proposed, which allows to perform exactly the
site-averaging procedure required when developing integral equation theories of
interaction site models of macromolecular fluids. It shows that no
approximation is involved when the number of Ornstein-Zernike equations
coupling the site-site correlation functions is reduced to one. Its potential
practical interest for future theoretical developments is illustrated with a
rederivation of the so-called molecular closures.
