When a person sells part if their property to a neighbor, it is not mapped by simply moving the boundary line. Watch this short video to learn how to properly map this recorded land transaction. This video was recorded using ArcGIS Pro version 2.8 in July 2021.
For further parcel data training, check out Esri's Working with Parcel Data in ArcGIS Pro course: https://bit.ly/3OtMMc9.