It will be fine and a treasured gift to your kids

I think you stated "a good quality muslin" I have used "a good quality muslin" many times and have not had a problem.

Just tell everyone that you were going for the vintage look. It will probaBly not move much if you have quilted it well.

Put a label on it to "wash: warm or cold" and dry: low or hang dry" In this day and age, using cold washing is almost as good as HOT and it doesn't shrink as much or lose the colors. I have been putting this on all my quilts. I know mothers with small children will have to use hot sometimes but with the other instructions, if there is a stain, cold water does best on removing many stains. My thoughts.

Perhaps you could contact Keepsake Quilting and see what they suggest. They may use one muslin for their kits and know how it washes.

I've quilted (hand quilted) the "medallion" and am almost on the outside portions. I've quilted at least every 3". I just hope this will be close enough... Maybe they won't look on the back and if it shrinks up too much, maybe they can use it on a full bed. I'll wash it when I'm finished and see how it turns out. Maybe I'll think better next time!