Hi Andreas,
The graph is the only graphic view where you can see all individuals at the same time in a family tree.
The dynamic tree view displays ancestors and descendants of the root individual you choose. This design comes from the fact that you cannot easilly display both an ascending line and a descending line for several individuals at the same time.
To see siblings of an individual, you have to choose a root individual among the ascendants of these siblings. Their father for instance.
Then you can navigate among individuals without changing the root in the tree.
I guess the direct answer to your question is to *not* change the root individual when you navigate from person to person. This is the default behaviour by the way.
I hope this little explanation answers your need, otherwise please let us know.
Cheers,
Frederic