We've been waiting for this one for a long time...
RDB Link Tool for Revit Family
Technology Preview (COMING SOON)
The RDBLink tool allows the user to export data from the elements in a Revit project and maintain relationships against data that exists outside of Revit. The tool allows for both import and export of the project data and will allow the user to make changes on the database side that affect the data within the project once imported. Also, during subsequent exports of the data to the same database, only data from the project will be affected, so any new fields or tables added to the database for your own purposes will remain intact along side the newly exported data. The RDBLink import tool provides a grid view of the data to allow the user to make any final edits before import. This grid control also allows the user to create Revit Shared Parameters which will add new fields for those parameters to the database in the related tables. Changes to these new fields within the database will update these Revit Shared Parameters upon future imports.
thanks RevitOPED for the tip