I always cringe a little when people say they use Sharpies on quilts, or permanent markers. They really aren't and will bleed into other fabric and if writing with them on fabric they will bleed and get fuzzy and faded.
I know from experience and I only use Pigma Pens or other Archival pens for making seams disappear and writing. They are one thing that is worth the investment. just MHO.
Wouldn't it be sad for a memory quilt of any kind to be lost to fading and bleeding signatures after a few years.
peace