and then copy the final performance to the Melodyne Plugin which is already on an adjacent audio track that is bussed back to the vocal track which has plugins on it and which I keep in input while editing in Melodyne.
My workflow is to record the vocal onto an audio track, edit ect. That's the one, obviously, that you use to bridge the standalone, which has spot capability, to P Tools. Yah, albee1952 was talking about the Melodyne Bridge plugin, not the Melodyne Plugin. You can't just select Pre-fade on the bus as that would be pre-plugins as well. The reason I usually don't bus and record is I usually have a bunch of other plugins on the track and that would record all of them, or require me to bypass and put the fader at -0(and turn off any automation I may have written already). It sounds convoluted, but after a few times, it becomes second nature. The tuned audio will spot exactly in the proper time(remember to bypass or remove the Melodyne Bridge plugin). The highlight the new audio and copy, then use tab to transient to find the same leading edge on your original track and hit Paste. Now I use Tab to Transient to find the first transient of the new audio and cut.
Your tuned audio will appear starting exactly where you left the cursor in PT.
Next, I go to Melodyne and hit File>Save Audio>make sure the check box is checked for "Spot to Pro Tools) and hit Save(or OK). In the edit window, I create a blank audio track next to the track I have tuned and place the cursor near where the audio starts.