Let's regard as an example the Mr John Doe's case. You have saved his birth dataset, and also the ones for his marriage and car accident. Those datasets are independant, i.e. you can freely delete any of them.

But if you save with Extract and Save e.g. the planetary positions for his birth, the directing and transiting ones for respectively his marriage and car accident, the marriage and car accident datasets are bound to his birth dataset. Both marriage and car accident datasets are called siblings of his birth dataset.

In the Dataset Search dialog box, the Siblings exists, which allows you to search for all the siblings to the first displayed dataset. In addition, the Delete permits you to delete either the stored planetary positions for the resulting sibling datasets, or even the datasets themselves. The latter operation is dangerous ! Be careful when you delete your datasets with this option.