To study the contributions of cusp outflow coming through the lobes and nightside auroral outflow to the O+ in the plasma sheet, we performed a statistical study of tailward streaming O+ in the lobes, the plasma sheet boundary layer (PSBL) and the plasma sheet (PS), using MMS/HPCA data. Similar spatial distributions demonstrate the entry of cusp-origin O+ from the lobes to the plasma sheet through the PSBL. There is an energy dependence in the lobe O+ spatial distribution, with low-energy O+ streaming near the center in YGSM while high energy (1-3 keV) O+ streams near the flanks. Low energy (< 100 eV) O+ from the nightside auroral oval can be identified in the near-Earth PSBL/PS with high-density (> 0.03 cm-3), and energetic (> 3 keV) streaming O+ with similar density (~0.02 cm-3) is seen further out on the duskside of the PSBL/PS. The rest of the nightside auroral O+ in the PSBL is mixed with O+ coming in from the lobe, and difficult to distinguish. We estimated the inflow and outflow of ions in the plasma sheet between 7-17 RE, using data extracted from previous studies and this work. Comparisons between the estimated fluence suggest that the majority of near-Earth plasma sheet H+ are from cusps and Earthward convection from the distant tail. The O+ in the same region, on the other hand, has a mixed source, with auroral outflow giving the highest contribution.