Also, use a machine with a large water capacity. The newer front loaders don't have enough water to wash away any furtive dye.

I've used this Retayne/Synthropol combo successfully on fabrics and clothing that bled (https://www.dharmatrading.com/chemicals/retayne.html), but that was on something that was all one color, so it wasn't a problem fixing any loose dye with the Retayne, because it was fixed to something the same color.

Since your quilt is all put together (and therefore NOT all one color), I think you might want to just use the Synthropol.

It was Kona, not Kona bay.

bkay

There are instructions on-line and I think it has been discussed here, a method for soaking quilts using Dawn dishwashing liquid to remove running or excess dye. I'm sure someone here can do a search for you, I'm not so good at that myself.

I Think I would stop washing and provide several (maybe a whole box) of color catchers with instructions to the recipient.

Kona Bay is getting hard to find since they are now out of business.

Several years ago I was in a Joannes fabric when they were having a sale on Kona and I personally witnessed them rolling their economy priced broadcloth solid onto a Kona bolt. The employee assumed they were consolidating the same fabric onto a bolt so they didn't have 5 different black solid bolts. Many of the employees at Joannes aren't sewers or quilters and to them a solid is a solid and they don't know or care about the difference. That incident convinced me to never purchase fabric there again.

This is true. My good friend had a quilting catastrophe and I sent her this link and it did fix the problem.
https://suzyquilts.com/fix-fabric-bleeds/

Almost all fabrics I buy don't bleed. Maybe a few have. I always prewash in cold water and use 4-5 color catchers. I use them until they fall apart. I only wash with cold water Tide.

I don't buy any expensive fabrics, Hobby Lobby and Walmart are good enough for me. I only buy quality fabric I can feel.

So sorry this happened to your Granddaughter's quilt.

That would be my suggestion also. I did this with a king sized Red and White double Irish chain, but I used Synthropal I put my quilt in the bathtub over night, and them it was just fine. Later I heard that Dawn dish soap, clear or blue worked just as well.