This function allows you to link the reservation of the commercial event in question to a previous reservation so that they both appear in the same segment. This option is useful if for example you wish to make two different commercials appears in the same segment.
The 'Assign Spaces from an existing reservation' window will be look as shown in the image below:
Using the filter you can search for specific reservations and then use the Reserve button (the horizontal arrow button in the toolbar) to schedule your commercial event in the same segment.
NB: Please note that only those order lines which scheduling type is different from top/bottom can be linked to existing reservations.