You're right but I can't convince her, she keep repeating me that she could edit pdf until now. I tried to call Adobe support to get an official answer but InDesign isn't supported by phone.
Thank you for your answer anyway.
either she previously had a plugin installed, or she was using Acrobat Pro, not InDesign.
You can Place a PDF in an InDesign document but you can't edit it. You can do some small amounts editing to PDFs in Acrobat Pro.
I wonder whether your client is thinking of an Acrobat Form, where users can add data to text boxes and so on.
Just a thought.
Thank you for your help, I send her your answer.
OK, I'll give you an official answer on behalf of Adobe ...
You can not “open” a PDF file for editing in InDesign nor can you edit contents of a PDF file placed into an InDesign document. Those are not features of the InDesign product.
There are third party plug-ins that purport to convert PDF files to InDesign format although such conversions may be fairly “lossy” depending upon the actual contents of that PDF.
There is also a terribly bad misconception that PDF files can be safely edited in Adobe Illustrator. Although Illustrator can “open” any arbitrary PDF file, the only PDF files that can be safely edited in Illustrator are PDF files saved from Illustrator using the “editability” option. Other PDF files are subject to color changes, content loss, rasterization/vectorization of text, etc.
PDF is a “final form file format” and you are always better off going back to the source files for edits.
Thank you for your help