is there any possible way to not lose any content, when inserting an image into a filled pdf, i am using the fpdm.php script from here and works prettty good i might add. the pdfs i am using i pass them trough pdftk, as in
pdftk.exe insert.pdf output output.pdf
All mentioned scripts are using FPDI in the background which simply doesn't modifes the original document but will allow you to recreate a completely new PDF document by importing another one page by page into reuseable structures (XObjects). Because form fields or other dynamic content like links or any other annotation type are not part of a pages content stream they will get lost.
The mentioned "magic" of the SetaPDF products is, that they modify the original document. Because of this all content will retain.