When creating a merge publication, specify the tables that are included as articles in that publication. If you include tables that contain foreign keys, the referenced table should also be included in the publication. If an attempt is made to add new rows to an article referencing a primary key in a missing table, the update fails because Microsoft® SQL Server™ cannot find the required primary key. If an attempt is made to simply update data in an existing row(s) of the article, the update succeeds because SQL Server does not have to add a new row(s) and key(s).
After they are created, merge publications can be modified to include additional articles. You can add any missing, referenced tables to a publication if you later discover that an article must be updated with additional rows and not just with modifications to existing rows. Use the Property dialog box for the publication to add the missing table.