I have been using Daylite for 2 years and want to import all my customer contacts into billings. Doing it one at a time makes no sense.

If I import slips, Billings creates a customer name- but with no associated contact information. If I then add the contact it creates a duplicate. and when I delete the first one - all the slips disappear!
I need to know how to do a mass import of contacts from Daylite to Billings