I have been using Ricky's Stable Stuff which is NOT fusible, but is wash-away.
Using Sharon Schamber's method of using Washable Elmer's school glue, I run the glue stick along the edge of my turn under applique edge, press (heat is important to good glue fusing) and then once again using the washable glue, glue it to my background.
The nice thing about Ricky's stable stuff is it is heavy enuf to use for the backing to keep the stitches from puckering up the background. (it's inside your turned under edge) and then when you wash it, it goes totally piable and soft.
I've made my entire Sue Garmon BOM using this method.
Good luck, Drew!
Lynn