Hi, Based upon our builders and retaining wall contractor's advice, our retaining wall was built straddling the boundary line, as we had excavated, and the neighbours had filled. This made the neighbours unhappy as they did not consent to having any of our retaining wall on their property. (We now know that, legally under property law the wall should have been built entirely within our boundary unless we had the neighbours' consent. Hindsight is a wonderful thing! ) However, after further discussions, they extended the retaining wall we had built to contain their fill, as they did not have a DA for a retaining wall whereas we did. They entered into a separate contract with the retaining wall contractor, and were responsible for all costs associated with the extension. We believed that this meant they now agreed to the location of the retaining wall. We were okay with this as it made everyone happy and both sides got what they needed. Or so we thought. The neighbours have now returned to their original stance that we built a retaining wall on their property without approval and are making legal threats. Being that the wall was 50% paid for by them, under a separate contract that had nothing to do with us, we are somewhat confused. We have no documentation where they specifically state they are okay with the location of the retaining wall, but doesn't their extension of the retaining wall imply this? Thoughts would be appreciated! Thanks.