Multiferroic materials which exhibit 2 or more of the ferroic order parameters continue to attract extensive attention. The most widely studied multiferroic is bismuth ferrite (BFO) owing to room temperature magnetic and electric ordering. However, high leakage currents and capacitances and a complex magnetic structure act as barriers to commercialisation. One way two overcome these problems is to dope either the A and/or B-site in these materials. We have recently been investigating the solid solution between BFO and sodium niobate; an importan ferroelectric. We observe a complex series of phase transitions with increasing sodium content. However, the similarity of these phases and the insensitivities of x-rays to oxygen (important in determining octahedral tilt) limits our understanding. We propose to collect complementary neutron data to further unravel this phase diagram.