  We revisited how Weinberg's ideas in Nuclear Physics influenced our own work
and lead to a renormalization group invariant framework within the quantum
mechanical few-body problem, and we also update the discussion on the relevant
scales in the limit of short-range interactions. In this context, it is revised
the formulation of the subtracted scattering equations and fixed-point
Hamiltonians applied to few-body systems, in which the original interaction
contains point-like singularities, such as Dirac-delta and/or its derivatives.
The approach is being illustrated by considering two-nucleons described by
singular interactions. This revision also includes an extension of the
renormalization formalism to three-body systems, which is followed by an
updated discussion on the applications to four particles.
