After splitting a check, you can always merge those checks back together:

1. Tap the Split check button on the bottom right of the Register screen below your menu sub-screens and items, which will open the Split check screen.
2. Select the button Actions at the top of the desired check, and the Actions window for the bill will open.
3. From this window, you can merge checks together by selecting the checks you wish to combine.
4. When you're done, select Merge at the bottom of the window.