Number of close-in (≲1 au) low-mass (≲95 M_⊕) planets per system in our sample. In orange is indicated the multiplicity based on the confirmed planets, while in gray, it is based on both confirmed and unconfirmed planets. Bins are centered on their corresponding multiplicity value, i.e., four systems do not have confirmed low-mass planets (GJ 649, GJ 682, GJ 832, HD 102365), even though at least one has been suggested in the literature (see details in Appendix A).