Frustrated magnetic materials are interesting because they show unusual behaviour arising from a near-degeneracy of ground states. The magnetic order of MgCr2O4 - apparently built from two symmetry-unrelated wavevectors - is an exotic example. Recent results suggest that magnetic order may involve frustration-induced phase separation into two nearly-degenerate states that couple differently to the lattice, leading to different lattice distortions from the cubic high-temperature phase. To test this hypothesis, we propose to use high-resolution powder and single-crystal diffraction to (i) determine if the magnetic structure is a single or two-phase; (ii) find the ordering wave vectors with respect to the low-temperature distorted crystal structure(s); (iii) solve the spin arrangements. Our results would reveal the nature of frustration and its coupling to the lattice in a topical magnet.