What a wonderful project. I think I would cut the largest square or rectangle from the pieces and treat that like a center panel. Then cut the rest of the quilt pieces into squares, all the same size. Don't know how big from your pics. Any smaller pieces that are left over I would have framed for family members. I would then arrange the squares with pieced blocks of the same size from your fabric. I would do a quilt as you go, so you wouldn't loose any of your dggm's quilting. Quilt your blocks individually, then join to her already quilted blocks using sashing. I'm anxious to see other's suggestions!!