The process of linking evidence to the curriculum is notoriously time consuming and infuriating. It is ridiculous that you cannot link more than one item at a time, either when linking from the curriculum to your evidence, or when linking from an assessment to curriculum items.
It turns out that the developers were not aware of this. And they can fix it (click here):
Things related to usability that don’t involve big changes to the content or structure of the existing site can be easily fixed. We just need to ask.