We are using Sharepoint as a relational database and are dependent on the custom identifier for unique values which can be referenced over time (stays the same even if the built in ID changes). The identifier works well from this point of view.
However, we build our relations using the lookup function and the custom identifier cannot be referenced in lookups. It is hard not to be able to pick a value using the unique identity (other non unique fields work).
Is it possible to build lookup relations on the custom identifer? If not, can it be fixed, or is there any work around available?