How to move lot of items into an existing collection?

Hi @tony.o , welcome to community! :wave:

The easiest way to do this is in the web vault - from the My vault view you’ll be able to multi-select and move all the items selected to the Collection(s) of your choice!

Just keep in mind that all of the items selected need to be move to the same Collection(s), but you can use the same feature again to move the rest of your items elsewhere.