We propose to perform neutron diffraction experiments on powder samples of possible spin-induced multiferroic materials, 114CdMn7O12 and SrMn7O12, at ambient pressure and low temperatures. A giant improper ferroelectricity was discovered in 2012 in CaMn7O12 with the polarization value of P = 2870 microC/m2. This discovery has stimulated a lot of interest toward CaMn7O12. We have recently described the high-pressure high-temperature synthesis, crystal structures and properties of CaMn7O12 analogues, CdMn7O12 and SrMn7O12. And we have found differences in magnetic properties, dielectric properties, ferroelectric properties and hysteresis behavior among CdMn7O12, CaMn7O12 and SrMn7O12. To understand the differences among AMn7O12 perovskites with A = Cd, Ca, Sr, and Pb, information about magnetic structures of all members is needed.