Germs of focus-focus fibrations –with respect to symplectic conjugation– are classified by formal power series in two variables $\mathbb{R}[\![x,y]\!]$ with vanishing constant term [33]. Such series correspond to the Taylor coefficients of functions $q\in C^{\infty}(D)$ as above evaluated at $0\in\mathbb{R}^{2}$. This means that there is an infinite number of different germs of focus-focus fibrations, all inducing simple affine manifolds with singularities, i.e. inducing the same singular affine structure on the base. In §4 we will see that a similar phenomenon happens in higher dimensions.