Step 1: Go to the SmallPDF website and click on the "Merge PDF" button.
Step 2: Click on the "Choose Files" button and select the files you wish to combine.
You can also rearrange the files by dragging and dropping them into the desired order.
Step 3: After uploading the files, select the "Merge Files" option.
Open a PDF file you want to combine in OneDrive for Android or iOS.
At the bottom of the screen, tap the horizontal bar or drag the bottom menu up to expand the new menu.
Under File actions, select Merge PDFs.
Choose the PDF file(s) you want to combine with.