One of the garments is a cardigan, cut from a more substantial fabric. Using a thicker fabric and sewing it with a serger means seams can have a lot of bulk when you have to fold a seam. In this case it's the seam of a neckband.
My solution is clip the seam at the point where it's folded, but not clip the thread that is forming the actual seam, press in different directions and fold over . The result doesn't show that much of a bump.
For comparison I made a quick sample of the result without clipping the seam too.
|The version which I made with the clip is at the bottom.|