We had older quilts at my mom's that rarely got washed. They never touched our skin and we had no animals inside. That being said, I would hate for that quilt to disintegrate when you wash it. Hope you figure out how to stabilize it. Otherwise just assume that you will have some fringing on the edges and embrace it.

Maybe some quilting within each butterfly or flower will lessen the stress on the outside blanket stitch and help preserve the project. I would echo stitch or go wild and do whatever appeals to you, the sun, stars, small butterflies within the larger butterfly.

It will fray a little but I think that's the charm of raw edge applique. I was gifted a raw edge applique quilt for my son who was born in 1977 and as far as I know it's still together.And I use Fray Block which dries clear and soft.