The occurrence rate of planetary systems resembling the mass and separation hierarchy of our Solar System is a central question in exoplanetology. However, observational efforts to determine these occurrence rates have yielded conflicting results, often due to limitations in detecting and characterizing outer companions such as the mass degeneracy intrinsic to the radial velocity method. While the release of astrometric candidates from Gaia DR3 represents a key asset in solving RV mass degeneracy, astrophysical false positives among such candidates still undermine the full exploitation of astrometric measurements.

In this talk we present the first results of an ongoing follow-up HARPS-N campaign focusing on a selected sample of stars hosting in the outer regions either a known massive companion with astrometry-derived true mass or a Gaia DR3 astrometric candidate. We identify binary stars masquerading as substellar companions and the first confirmation of astrometric candidates in the sample, as well as new low-mass planetary companions on inner orbits representing the first steps towards an improved determination of ordered system occurrence rates.