Is it possible to filter what relationships are displayed in the relation graph?
No, it is not possible. The actual Relations Graph is an old CMDBuild component with some limitations.
In the coming 6-8 months we will rewrite it with new technologies and additional features that will allow you to select the "domains chain" to display, show dependencies between elements of the graph, explore cluster of elements normally not diplayed because of their quantity, etc
CMDBuild Team
As an update, in 3.3 (maybe earlier versions) “Navigation Tree” concept is introduced to filter relations displayed in the Relation graph