PDF Master Needed for Advice

I am seeking advice on a programming issue my client is facing; this project involves no actual work other than perhaps some research. My client is only going to pay for advice that leads to a solution to his problem. Situation: We have been dealing with PDF files and how to populate them with data. My client's website's users will be uploading PDF files; this means we do not always know the content on them beforehand or even if the PDF is interactive. Possible Solutions: #1 - Users pay a small fee to create an interactive version of their form. Form fields would correspond to variable names; I can use these variable names to populate the form. #2 - We create functionality like DocuSign where the user clicks on a canvas (with the PDF loaded on to the canvas) and then starts typing. #3 - Have the user enter information into forms. Use a programming language such as ColdFusion, PHP, ASP, JSP, etc to create the needed form. #4 - A combination of the above. Try to think of a solution that we have not thought of. There are issues with the above solutions in that my client wants a solution that will work in all circumstances. Include the term "PDF PRO" in your bid description or it will be ignored. This is to make sure that you actually read the project description.