You'll link to the secondary table twice - once from each region field from the primary table. When you try to add a table to your report that's already in your report, Crystal will let you know it's already there and ask if you want to alias it. At that point it will add the table to the report with "_1" at the end of the table name. So, if your table name is "Secondary" you'll also have "Secondary_1". If there's any possiblity that one of the region fields will have data an the other won't, you'll want to make sure these are left outer joins from the primary to each of the secondaries.
-Dell