Hi
You have to have both clips on the same track to fully use any transition correctly but you can fade- in/fade-out a clip whichever track it is on. Borate and myself have looked at this in one of your earlier posts and I think this might work for you. It's pretty straightforward and you don't have to splt or unlink anything as we initially thought It's not 100% but it IS workable......
Place both clips together on Video Track 1
Pull up Clip 2 to the overlay track and drag it left for the full duration of any transition (e.g. 4 seconds)
Add the circle transition to Clip 1 for 4 seconds
Add a fade into Clip 2 using the f button that is on the clip. Make it 4 seconds.
Clip 2 will now fade in through the circle transition.
Sound tracks can be faded in/out as required.
Everything remains in sync
Nat