Antiferromagnetic S = 1 one-dimensional chains exhibit a myriad of magnetic ground states depending on the balance between the spin exchange parameter and the single-ion anisotropy. We propose a neutron powder diffraction experiment, to be performed on WISH, in order to determine the magnetic structure of magnetically chain-like coordination polymers [Ni(HF2)(pyz)2]SbF6 and [Ni(HF2)(pyz)2]PF6. In doing so we will test the predictions that one polymorph of the latter material exhibits XY ordering, while another has a Ising-like ground state. We will then measure the former material as a function of pressure to ascertain the evolution of the magnetism across the phase diagram previously mapped out by Diamond experiments. In particular, we will determine whether the structural phase transition observed leads to a predicted change in the universality class of the magnetic ground state.