I have done hidden tying on Quilts. Get very long needles. Double your pearl cotton or whatever you are using to tie and leave the ends buried in the quilt. Take the thread inside the quilt as far as you can go, bring it up, make two loops tightly through all layers and take it back in the layers to the next spot. Repeat. Nice and tidy and no ends to get into trouble. If you make the spacing about 3" apart on a grid pattern it will hardly seem to be done but still be nice and tight.