Split
1. In reservation view (view mode) of the reservation you want to split, click 'Split' in the options menu in top right corner.
2. In the page that opens you can see all rooms of the existing reservation in the left side.
Drag the rooms you want to split to a new reservation to the right side, and click 'Apply' in top right corner to make the split.
Move
3. Use the search box above the right column if you want to move rooms to an already existing reservation.
4. Search and find the reservation you want to move the rooms to.
5. Drag the rooms you want to move to the exsting reservation to the right side, and click 'Apply' in top right corner to move the rooms.