Merging PDF Documents

Please can someone tell me if this is easy to do or whether I should use a package already available... I want to upload a pdf file to a folder then for each subsequent upload, I want it to be appended to the original file. Each pdf is a timesheet, so I want to end up with one file for all timesheets instead of different files every week. What I'd like to know is which function I can use on PHP4? Is it PDF_begin_page_ext? Any help appreciated. Thanks, Tom -- Tom Chubb tomchubb@gmail.com