merge excel files into one join lines into one all into one merge multiple pages into one combine into one pdf combine pst files into one merge txt docs combine webp files into one combine mkvs into one file all together into one image combine powerpoint into one combine pdf files into one merge pdf files into one combine excel cells into one join many images into one file merge lines into one line join xls files into one merge 2 pdf pages into one join 2 or more combine+pdf+files+into+one