The doping of Mn sites with Co and Ni was studied for Ca0.85Sm0.15MnO3 and Ca0.80Sm0.20MnO3 and compared with Cr doping in the same oxides. It is shown that the three dopants induce strong ferromagnetic interactions and metallicity in both manganites, and that they destroy CMR effect in Ca0.85Sm0.15MnO3 and induce CMR effect in Ca0.80Sm0.20MnO3. The optimal doping level x for reaching the maximum resistivity ratio is larger for Cr (x = 0.08) than for Co and Ni (x = 0.06).