Were she to do that, single-sided fusible would be better: just adhere it to the top fabric. But it won't be a long-term fix if the silk is rotting.

Is it a crazy quilt? If so, I would find something else - fabric, applique, etc. - and appliqué it on top. I would hand sew it to the adjacent block and just re-do the yellow stitching. That is an easy stitch and easy thread to find.

I was curious about this problem so did some searching. This looks like a good tutorial on repairing crazy quilts. It just repeats most of what latifolia said, but has photos.

bkay

That was an interesting tutorial.

Theresa

Thank you, latifolia. I sent her your suggestion right away.

bkay, thanks so much. That is a very helpful tutorial. I'm not sure she can handle that with her sewing skills, but what she does sew is perfect, so she may. I'll post pics if she is able to repair it.