Have you been using more than one Lightroom catalog, maybe starting a new one with each new year, or keeping your family images in separate catalog from your travel images? If so, you know that this puts a brick wall between images in each catalog, making it very cumbersome to pull together groups of photos that span catalogs, such as your best images of all time. I therefore strongly recommend that most people use just one catalog unless you really you need that brick wall. If you’re afraid that your catalog might have too many images in it, consider that Adobe has found customers who have millions of photos in one catalog!
In the video tutorial below I show you how to combine / merge two or more catalogs into one. This video is one of 101 in my Lightroom 5, 6 and Classic 7: The Fundamentals & Beyond video series, providing 22 hours of training for beginners and experienced users – do check it out (Videos for sale are larger and are not blurry.)