Template to be instantly filled out with info from another spreadsheet

Hi there.
I'm wondering if the following is at all possible. I have an invoice template which I use for all my recurring customers. It takes quite some time entering their information each time into the template so I started making a personalized template to each customer. The problem is that it's taking way too long to do this and there will be tines that the template would have to be modified and then I would have to start the whole process of making a personalized template for each customer again. I was wondering if I can have a spreadsheet with all my customers on it and their relevant information and have one base template which would have a little box on the top and when I enter a specific customer from the customer spreadsheet and click "enter" all that customers information will be filled out instantly.
I hope this can be done.
Thanks in advance

If you send a PDF file and not a xls file to your customer they can't see the other customers