In Relationships view, allow the user to select multiple fields in one table and create a "key"
When in Relationships View - allow the user to select multiple fields (with ctrl) and click a tool button that creates a 'key' field (custom column) concatenating the values from the selected fields. This way the user can create a relationship between two data sources when multiple fields are the link between them, right in the relationship screen.
Yes. This would make building relationships so much more streamlined.