Somebody else asked the same question today. For starters, see this thread: How do I merge files
Many details have to be manually created from scratch after import. I haven't checked to be sure, but I suspect that a validation calculation that refers to a table occurrence that does not yet exist in your merged file will be enclosed in /* comment brackets */--which enables you to recreate all your table occurrences and relationships, then you can go in and edit them to remove the comment brackets. Other noncalculation validation rules such as what you have here will likely have to be fixed manually.