Thanks for the reply, Greg. Based on the use cases for the facts in the database I'm dealing with, I don't think any fact tables will reference more than one entity of the dimNames table at one time. So I think I will retain an "IsBusiness" flag column but I will leave the business name as a LastName value, just as it is in the OLTP. If I build a view exclusively for businesses, I will just put an alias of "BusinessName" onto the LastName column.

Speaking of the "IsBusiness" column, would you recommend that this column be a bit data type or should it be a varchar for literal "Yes" and "No" text? I ask because I know a data warehouse is supposed to be about making the data accessible to non-techies and to that end it should avoid "codes" for values. But I also know that a bit data type is much more efficient for storage and for querying than is a varchar data type.