When I made the Farmers Wife Sampler & FW Pony quilts this is exactly what I did. I quilted each block/batting separately then joined them with sashing & cornerstones. Then I put the back on in one piece and just quilted the sashing and cornerstone areas to "attach" the backing. I know some purists will gasp, but this is what works for me. The front is nicely quilted but the backing just has a grid quilted matching the sashing. (who looks at the backs?) I didn't want to do the back in squares with sashing like most QAYG sites teach; just don't like that much hand sewing anymore.