Notes/Domino 4 and 5 Forum

Dear all expert,
I have a filed zNRouteTo which is a dialog list for address. User can select who to route to to by using this address dialog list. But I would like to use @dbLookup in this field where if it is empty, @dblookup will perform to search the correct recipient in another database.

Where should I place the @dblookup formula as there are Default Value, Input translation and so on within the zNRouteTo field.

any advice?

Thank you.