I'm writing this here to increase my chance of remembering when I'm at home.
I have a broader neck than average, so I cut the neckline of this dress wider. I remembered to cut the back neck facing wider, but not the collar, so I'll need to reduce the seam allowance on the undercollar to compensate.
I haven't cut the upper collar out yet, as I decided that rather than have one end with an interest point and the other end without as the length of the collar piece just doesn't work that way with this print, no matter where I moved it on the piece of fabric left for it.
So long as there's a CB seam on the collar, I think I can cut them with a swallow on each point, and both facing in the same direction. I'll need to make two half collar pattern pieces to ensure that the layout doesn't overlap before I start cutting. I could chalk one and then flip for the other end, but to be honest it's no harder to cut two pattern pieces.