You can't import it all at the same time. You import twice from the same file, designating a different target table for each import. (For manual imports, you select a layout based on the target table in order to import records into that table.). Since the customer data is likely repeated over and over again, you'll want to set up a validation rule that filters out the duplicated values during import to give you one record for each customer.
But this assumes you have a column in your tab file that uniquely identifies each customer and a name is not likely to work perfectly for that purpose. Do you have some kind of customer ID column in this data?
I can definitely import twice (once for each table). But the bproblem with that is connecting the two data sets afterwards. Is there a way I can make an identifier to make the records (Customers & Orders) recognize each other and link up after import?
To answer your question, each order in the table I'm trying to import has it's own unique identifying number. The customers do not have identifying numbers, but every single customer on the list has a unique email address. Most of the orders are one time orders. Only a handful are repeat orders.
Is there a way I can make an identifier to make the records (Customers & Orders) recognize each other and link up after import?
The Order number column can be used for that purpose, but what you really need is to match up orders to customers by Customer or you get duplicate records in the Customers table for that "handful of repeat orders".
Best bet is to import the email address field into text fields in both tables. Set the unique values, validate always field options on the customers table, to eliminate duplicate records in that table. Then tempoararily link your two tables by email address, but use an auto-entered serial number field in Customers to link to a number field once you have the data imported.
A Replace Field Contents operation can copy the serial number value from customers into the match field in Orders after you have imported the data.
You database, BTW, can use separate table occurrences to link orders and customers by email address in one relationship and by CustomerID serial number in a second. That way you can use the first relationship to set up the second.