Got it to work! Thanks for your help!
Demo for adding items:
I was also able to find out a way to delete the items from the bucket, however it’s very inefficient. I have a “Remove items” button that links to the ItemsToBuckets sheet, then you select an item from the bucket and delete that item. So it adds a bunch of steps just to delete the item. Do you have a more efficient method?
Demo for removing an item: