The compound "manganese(III) formate" appears crystallographically to have a cubic ReO3-type structure, but in fact magnetic and optical measurements reveal that the Mn coordination octahedra are likely to be Jahn-Teller distorted. Furthermore, the pores of this material contain disordered CO2 and formic acid guests. We propose to measure total neutron scattering from this (perdeuterated) material in order to determine its true local structure. Using the reverse Monte Carlo technique, we will model the correlations between the distortion at the Mn ion, the guest occupancy in the neighbouring pores, the local distortions to the framework structure, and the magnetic fluctuations in this material. Teasing out these complex relationships will help move towards multiferroicity in the closely related "metal-formate perovskites".