This proposal seeks to determine the structures of the high temperature phases of SrNdNiRuO6 and to investigate the nature of the transitions between them. Iturbe-Zabalo et al. recently reported a unique sequence of structures in the double perovskite SrNdNiRuO6, P21/n to P42/n to Fm3m, that violates the hierarchy established by our group theoretical approach and by doing so throws into doubt the validity of this. This work aims to resolve the conflict between the X-ray diffraction study of Iturbe-Zabalo et al. and the results from our group theoretical analysis.