When creating a master-detail report, some of the master-detail bands (subordinate items) may be moved to the first page and some to the next page. This may be caused by not all detail records fitting on one page. If you still need to print the master and its details on one page, you can use the KeepDetails property. By default this property is set to false.

The image above shows a report with some details on one page and other details on the next page. If the property is set to true, the report generator will try to put master and detail records on one page. If the report generator cannot do that, it will move the master and detail together to the next page.

Above is an example of a report with the master's KeepDetails property set to true. Otherwise, the data will be forced split and displayed on separate pages. In this case, if the master component has many detail records and is a significant part of the page, and the KeepDetails property is set to true, you may end up with a large empty space at the bottom of each page. I have.