Buttonhole Puzzler

Work continues on my Cutting Line Designs Anything But Ordinary coat. Right now I'm trying to puzzle through the slot buttonhole at the neckline. As mentioned in my previous post, Louise has instructions for gorgeous slotted buttonholes at the Threads website here.

The technique requires that seams be pressed open. The slots are formed by leaving a gap in the seam. This worked great on the lower two button holes but I'm perplexed about the one at the neckline.

I made a mistake (well, lots really, but who is counting?) when I thought I could enclose all those SAs in the collar. That does not leave a way to put the gap in the seam for the button.

So off to rip a few stitches.

Any ideas?