Preparing a document from a template

I have a bit of an odd question, and I will try to word it as best as I can. I use Sign to send contracts to customers, it is always the same document but different values. Some of the values are input in an excel document and calculated before being saved as a PDF and uploaded to be prepared. The other values are input by the customer and are always the same fields on the PDF. Is there a way to create a template and then have those select values prepared on the PDF exported form Excel?  Basically what I would like to do is be able to prepare the spots for the customer to complete from a template, but be able to upload a different PDF for each customer. Is this something that is possible?