Schluter tile edge transition to drywall

I have a customer who has his shower tiled with the Schluter edging along the top. There is some drywall damage and a general gap now between the time edging and the hardie board drywall. I'm filling in the damaged gaps with joint compound and plan to thinset apply kerdi band to water proof the gap.
Should I apply the Kerdi Band along the wall, continuing behind the tile, (and use caulk to seal) or put a slight corner on the Kerdi Band to seal the tape to the Schluter edge, (using caulk to finish)?