There's a difference between a Datasource table and a table occurrence. I've included a link below if you want to read up on the differences.
For each portal, you'll need to identify the table--not the table occurrence box in the relationship graph which may or may not have the same name. Double click the portal while in layout mode and note the table occurrence name that appears in the drop down in the top of the portal setup dialog that pops up. Find this table occurrence in your relationships graph and double click it to find the name of the data source table.
Now go to a layout that refers to this data source table or a table occurrence that has the same data-source table. If you can't find one, make one. It can be blank as long as it identifies the correct table occurrence in layout setup...
Now select Import records from your other file and specify the data source table as the source of the records you will import.
Many folks find the terms Table and Table Occurrence confusing. To learn more, click the following link:
Table vs. Table Occurrence (Tutorial)
Hi Mr. Caulkins,
Thanks for the clarification between TO and data source tables. I appreciate it. I am going to try what you suggested and hopefully it works.