The doping of Mn-sublattice by magnetic cations M = Cr, Co, Ni, Ru in half doped manganites Ln 0 . 5 Ca 0 . 5 MnO 3 and in Mn(IV)-rich manganites Ln 0 . 4 Ca 0 . 6 MnO 3 , induces an insulator to metal transition. The appearance of metallicity and ferromagnetism in those doped manganites is explained in terms of models based on phase separation scenario. Coexistence of ferromagnetism and charge ordering is demonstrated in the Cr-doped manganites, whereas ferromagnetic metallic clusters are formed around Ru in the AFM matrix of Ru-doped compounds. The participation of Cr 3 + , Ru 4 + and Ru 5 + to double exchange is discussed, taking into consideration the isoelectronic character of these ions with Mn 3 + and Mn 4 + species.