Regarding Adverse Possession In Texs

We are currently in negotiations regarding a neighbor who is trying to take adverse possession of 5 feet of my mothers residential property. We recently had the property surveyed which showed that our property line is 5 feet extending from our fence line. This is not news to the family because both families knew that the our property line extended further than the fence. We were in the process of building a new fence for my mother house when we had the property surveyed. The surveyor stands behind the survey and so does the city. The neighbor put up a partial fence appoximately 7 years ago without my mothers permission. My mother is elderly and does not understand the laws as they stand. After researching their property deeds, it was found that the neighbors house was part of an estate and the family member who is trying to take possession bought the house in 2002. He does not reside at the home and has not been there for several years. He does have items stored on the property but lives in another part of the town. The house has been vacant for several years and to say the least is an eye sore. We are ready to go to court and are wondering since he has had sole possession only since 2002, do we have a chance of winning this case