Is it possible to change calendar exceptions through import?

Hi,

one of our clients uses calendar exceptions to model weather non-availability.

I try to update these exceptions by manipulating XML exports and import them again, but this only seems to work if I import it as a new calendar.

Is it also possible to bulk import changes to exceptions in existing calendars?

I know it is possible to model weather risks in the risk module, but the above method is an industry requirement.

Thanks!