Let's talk about Aurelius itself for a while and leave Data Modeler aside. You can't have mapped fields in non-entity classes. In other words, if your ancestor class TObjectWithUserID is not going to be persisted in a specific table, you should not have your userid property mapped to a table column using [Column] attribute. Even though you have that field in ancestor class, you should map it in each descendant table. Usually users do this:
TObjectWithUserID = class(TObject)
property UserId: Integer read FUserId write FUserId;
TSomeClass = class(TObjectWithUserID)
That way you have the regular OOP inheritance (UserId property is in the ancestor) but your mapping is specific to each descendant object - because persistence of that field is conceptually done in different table columns. In theory you could have the userid property of class TClass1 being saved in Table1.UserId, and the same userid property of class TClass2 being saved in Table2.USER_ID.
Having said all that, TMS Data Modeler doesn't build that construction automatically, unfortunately. It maps fields directly (not properties). So you would have to fine tune the source code it generated. Note though that Data Modeler 3 has scripting capabilities that allow you to find tune the generated source code through Pascal script.
In this case for example you could create a script that declares a property userid and adds the Column attributes to it for all Aurelius classes.