Our aim is to investigate the chemical and magnetic structure of the charge ordered (CO) AFM and charge disordered FM phases of La5/8-yPryCa3/8MnO3 down to 2 K and study the variation of their relative phase fraction under zero field cool and field cooled conditions. The magnetic structure changes during this re-entrant (CO) transition are missing in the literature. The H-T phase diagram constructed using XRD studies shows that the field requirement to transform the AFM to FM first decreases with decreasing temperature down to 39 K and then increases with further decreasing temperature down to 2 K. The origin of this phase diagram actually lies into this re-entrant CO behaviour. Our preliminary XRD study demands some strong proof to conclusively present the results. The melting of CO phase will be studied studied by performing the neutron diffraction under external magnetic field.