A tree always start with a person. You can view and print :

1. The ancestry of a person (the ancestors)
   
   
2. The descent of an individual (children, grandchildren...)
   
   
3. A mixed tree with ancestry and descendant

You can’t have all the ancestors and their brothers or sisters, cousins (collaterals)

If you want siblings, you need to start with the parents and view a descending or mixed tree.

If you want a tree with the cousins, start with the grandparents