I would like to add my 2 cents, for what it is worth. If she has already cut the t-shirts, I would use fusible grid to make the quilt. I always use the grid and it makes it practically fool proof. Cut the shirts to and even inch number, 10, 11, 12 inches, etc. Fuse to the grid using an applique pressing mat ($15 - $20), leaving room for sashing, 1, 2, or 3 inch. Once t-shirts are fused then fuse sashing between. Fold and sew your seam on all lengths and whalla, done! Except for a border if you choose to do one. Got the idea for doing it this way from this site....
http://www.crookednickel.com/memories.html
They have some small demo vidoes to watch.
Sheila