was going to suggest similar. Adding the new k/words is done only when you have time or file/keywords pop up during a search. Don't try to do all tonight sort of thing .All new photos go into to new system of course. Make sure you remove the old keywords from the files. I still have very old ones showing up at times as I have messed things up big time [really BIG time] a few times .Create one item as a top level of a hierarchical list. Call it something like "Old Keywords". Select and drag all of your keywords onto this new top level keyword ("Old Keywords"). Create new organized keywords at the same level as the new top level keyword ("Old Keywords") If you have existing keywords that are good or can be renamed to be a "good" keyword and are now children of the new top level keyword ("Old Keywords") you can drag them outside of the parent ("Old Keywords") In each existing "dirty" keyword select all of the images by clicking on the arrow to the right of the "dirty" keyword. For each image in the grid view of this "dirty" keyword, create or assign a new appropriate keyword and remove the "dirty" keyword from the image. The image will disappear from this grid view. When the image count for the "dirty" keyword reaches zero the grid will be empty and the keyword can be deleted. Repeat for all "dirty" keywords until there are no more under the top level keyword ("Old Keywords").