Add Customer Name Into Table Each Time Unique Customer Added To SaleTable

I have a Table Sales - that lists customer and order information

Most of the customers are new - is there a way to populate Customer Name Table with a new entry each time a new customer is input into the Sales Tale

(Without having to add the custome to Customer Name Table - then going to Sales Order)
OR
Failing that - is there a way to use a list box that points to Customer Name Table (and if it doesn't find the one you want, will allow you toadd a new record) In the SAME form as you use to add to Sales Table.

So:
Date (textbox linking to form.Sales) Customer Name (List Box linking to form.CustomerName + adding the info to form.Sale)