Okay, I will try to explain how I do my Y seams in the "May" Block
1.The first photo shows the 2 pieces of fabric sewn on the center seam with a pin going thru at the end of the stitching of the "V".. I lifted the paper to mark with a pencil a dot right where the pin is at the end on both sides of the 2 fabrics. this is where the pivot will be. I started the seam at the bottom and finished at the solid line of the "V" back stitching so the "V" won't open when tugged on..remove from machine..because the seam allowance is exposed you can't sew over it..
2.The second photo shows where I removed the paper carefully at the center seam repositioning it so that the paper should be where it was when it was a solid piece.. BUT the seam allowance is exposed..You'll see how easy it is to manipulate the fabric..I taped & pinned the paper sections in place. the blue side was sewn from the outer edge to the exact spot where the pencil mark is at the "V"...
3.The third photo show no back stitch..I fixed it after I took the photo.
4. The 4th photo shows a pin at the end of the green piece to be pivoted and pinned at the point on the other side of the scottie fabric it will be joined to. you'll see how easy the "V" swings around. push the pin thru and flatten the section just pinned. I check with a pin pushed thru both pieces at mid seam line to see if the lines match up ..
Stitch from the outside edge to the pencil mark on the "V" making sure you sew to the seam line of the "V" and back stitch..
5. the 5th photo is how nice & flat the section will lay after you adjust the seam & press..