Question About Updating Table From A Form

Help - I'm at a loss! I have a form that I am using for invoicing for a Trucking firm. On this form, I have three fields that I am having problems with. These fields are From, To and Mileage from a table named Location. The user selects "From" from a combo box then goes to select "To" from another combo box. The "To" field is a filtered list of only those locations which correspond to the "From" that was chosen. Once this is done, the corresponding mileage is automatically filled in and used for rate calculations. If the "To" that they want is not in the table, they can double click the field and a form to add a record to the table pops up. So far, so good.

My problem is that now the user wants to be able to add a record such as New York to be From and Miami to be To with 123 as mileage once and be able to have Miami as From and New York as To with 123 as the mileage if he needs on future invoices. Can this be done without having to enter it again?