My only advice is to buy the best flannel that you may afford. I am in the middle of putting a new back on my GGD quilt. The original quilt was made in squares and I used quilt as you go (QAYG) method. The flannel on the back, literally shredded at the seams and many seams came apart. I'm putting a Shannon Cuddle Minky on the back now (over the flannel), new binding and I must do a new FMQ to hold it all together. Believe me! You won't want to have to do this. Good luck! For me, it was lesson learned the hard way.