Page breaks are useful to get a better overview of your FTAs. The page breaks will not influence the probability calculation of the whole system.
In the editor, right-click on the desired gate/malfunction (not event) where you want to situate the page break. - Outcome: The context menu will open.
Choose Create page break. - Outcome: The page break will be shown as a triangle.
Double-click on the triangle to open the page break.
Double-click on the triangle under the malfunction to get a level above.