Hi QN: I quilted my blocks and batting. Then I added the sashing and sewed rows of blocks. I sewed 3 rows together then added the backing to that section. I then quilted the sashing and cornerstones in that section. I added the other 2 sections of 3 rows and did the same. I handstitched the backing together where the sections joined. Does that make sense? It worked for me. There's not much quilting on the back-just the sashing and cornerstones so it just looks like a large grid on the back. I did my borders the same way. It was easier to do than try to type this--I hope I make sense to you LOL!
I plan on doing Pony Club quilt the same way. I have chronic tendonitis in my shoulders and just can't manage a large quilt on my small machine (getting old sucks). I also have a tendency to not finish quilt tops--this way I got it done.