My main problem with birthing any quilt is, I can never get the top and back to stay lined up perfectly after the sandwich is turned right side out. ( Back puckers and the edge seam not exactly along the edge)It sounds like you want to birth the quilt and then apply Elmer's washable glue to bast the quilt through the opening? I have never tried that so you will have to tell us how it works if you decide to do it. I think it might be easier to spray inside it with 505 because you can peel it up and reposition it if needed.