You can use PDF Reader Pro to merge your PDF documents into a new PDF file.
1. Enter the reading page and tap Editor on the toolbar.
2. Tap Merge to combine multiple PDF files into a new PDF document, and you can also borrow individual pages from other PDF files to merge.
3. Tap Add Files + to add documents that you want to combine together.
4. Set the Page Range by selecting All Pages, Odd Pages Only, Even Pages Only, or Custom Range, so that you can decide which specific pages need to be merged;
5. Click Merge to start combining files into a single PDF.
6. Alternatively, find Merge in Quick Tools on Home to quickly complete the PDF merging task.