DexExpress XPO Code First makes sure you spend a minimum amount of time in the Database, because you can manage the structure of your data solely in code. This is one of the stronger points of XPO compared to other Object-Relational Mapping frameworks.
However, there are some cases in which changes in code are not persisted in the database. This is unfortunate, because it weakens the Code First approach. The case of this article is: if you remove the inheritance of one object to the other in code, the Foreign Key relation in the database is not removed.