Help! One of the triangles..
 

...around the edge of my on-point quilt top was cut too short and I need to replace it. I can take it out with a seam ripper.

What is the best way to get another triangle into that space without having to take the whole row off?

I was thinking of trying a y-seam?

Clear as mud?

Watson

Just unsew the seams around it about an inch or two. Add the new triangle and resew where needed

Yup, Y seam is the answer. Sew one edge on, starting 1/4" from the ( inside tip) stitching out to outside edge. Then, fold other side together, start at outside edge & stitch in to the point. Or, you can stitch ( out) from center on both sides. I just find it easier to do one in one direction, other the other way.

You should be able to just take both seams out an inch or so past the intersection and avoid the Y.