As you have by now figured out, transitions can only be added to the "native" video track in Power Director, so if you're intending to add video overlay on a PiP track and want to add a transition, it may be best to join the two wanted clips together for this purpose as a separate item, giving it a name like "insert item" or something like that. If more than one of these are required, given them numbers, e.g. "Insert Item 1, 2, 3 and so on. These could be short bits that, on their own are less than 10 seconds duration but together may add up to 15 or 20 seconds, depending on the length of the transition. Transitions do eat up some of your running time. If you set your transition effect at, say, 5 seconds, each time you add a transition, that's the amount of time by which your video work will be shortened. If you're using Corel Video Studio, you can add a transition between two clips on a PiP track but you're restricted to 1-second duration. Just a tip.