I was just sitting around and thinking..you know where I was...and it occurred to me that sandwiching the quilt after placement of the appliques and before sewing down the applique, then sewing down the appliques would serve to quilt the piece at the same time. Is there something wrong with this theory? It seems plausible but maybe not practical...

nothing wrong with it at all! i've done it with a few projects- then used sashing strips to put the blocks together- worked out great.
you can also embroider the same way- and quilt as you go= sometimes it's a real time saver- sometimes it really enhances the appliques or embroidery-more so than waiting to quilt when it's all done.

Machine or hand applique? Depending on the size of the quilt, it may be difficult to handle the quilt to do this. Is this going to be a wall hanging as it would not matter much what the back looked like?

I say GO FOR IT! Just send pictures.

I have thought of that too. I think it should work just fine if the quilt isn't too big. Let us know how it goes.

I did a tester for a quilt designer in the US and it was my first applique and she said she always layered before she did her applique so I have done it ever since, although on larger quilts I use an adjusted QAYG method.

Maybe make a little sandwich and then sew the stitches on it you are planning on using for the applique. Sometimes you may not want a satin, button hole, or other stitch showing on the quilt back. Other times it may be a design element you really like.

I find it difficult to constantly manuever a quilt in my machine to stitch around the pieces on a quilt bigger than baby sized. You will need to constantly spin the quilt around to get around all of the edges. :D:D:D

Thanks Ladies for the sound advice.

I always do that with stain glass applique because to do it afterward is very redundant