In order to add events from different plays to a page of multiple events, follow these steps:

Click on the "Administration" tab and then click on "edit" under ''festival''.

Select from the dropdown menu the play you have set as the festival page:

Click on the "festival events" tab

Then click on "add events that wiil be shown at the festival".

On the pop-up window, select the events you want to be shown on this page and hit "save".