rotate object in relation of sth. else

[Penguin]

Probably a simple question:

How do I rotate an object (node3d) in relation to another objects local coordinate system?

For instance, I want to relatively rotate object1 by 1 degree in relation to the z-axis of object2s local coordinate system (roll of 1 degree according to object2).

In another example I want to relatively rotate object1 by 1 degree in relation to the main view (roll of 1 degree according to main view).