My father and I purchased a home in October 2008. Since then our neighbor has been encroaching onto our property with his rock garden. Every year he pushes towards our house. It has pushed past the line of a pre-existing chainlink fence. Yesterday we went to our township offices to get a better idea of our property lines and discovered that there is a 20' "alley" between our two property's and across our backyard bisecting our lots. The lot map that is still registered with the state of michigan is from 1918 and according to the township assessor is still valid. This alley is no longer existent. The realtor never told us that the property was bisected and that we don't actually own 20' of our backyard. What should I do?