Hi there! My name is ***** ***** I'd love to help you with this issue.
From what I can understand you are using Filermaker Pro and instead of saving the document as a Filemaker file type (such as .fmp12) you are saving as a PDF and then you send it to the customer. So when you have an issue where you need to modify that quote, you need to start from scratch which is a total waste of your time since Filemaker Pro won't open the PDF you saved. Is that correct?
If yes, 3 options:
1) Save as both file types (Easy, but more files to keep track of and adds extra step to your workflow and a bit more files to store on your hard drive).
2) Save as the Filemaker Pro File type and when you want to send a customer the file, save as a PDF and then delete it. (Similar solution, but you don't need to worry about keeping track of both files. However, you will need to recreate the PDF if you need it again even with no modifications. It would be in your sent email though, so perhaps that's not a huge issue, depending on your workflow).
3) Get a plugin to read the PDF files for Filemaker Pro. Here is a list of 3 I found for you.
(This will cost money and time, and you have another program on your computer. It would give you the ability to pull in other PDF's which may or may not be of use to you. Also, it may or may not read the PDF the same way as you created it since it will have to go through a conversion. I'd suggest options 1 or 2 for you, but this is available).
I hope that sheds some light on what you want to do. Please do let me know if I've misunderstood your question or you just need more help! If what I gave you takes care of your issue, I'd greatly appreciate it if you would rate my help today. Thanks!