Increases for garter mitered corner?

I added a small placket to the front neckline of WhiteLies Shapely Tank. Neckline border is only 6 rows of garter and I want very crisp, square turn from the placket to the neckline. By PU on RS, working WS, and then doing incs in the 2 remaining RS rows that only gives me a total of 4 incs at each turn/corner which I fear isn’t enough. Any way to intro 2 more on each? And is KFB my best option (don’t want YO eyelets)?

Never mind. I fig’d out what I needed to do.

TIA,
cam