Seems my original pics disappeared. I have made a new set of pics since I couldn't find the originals. This set is joining the rows instead of the individual blocks, hopefully they will make sense to you. This quilt has more of an obvious sashing, so you can do this method on both an obvious sashing quilt and a "hidden" sashing like my En Provence. My grey sashing fabric is not quilting cotton so is a little more unruly the quilting cotton works up perfectly so don't let the bumps and puckers of the grey fabric discourage you from trying this method, my grey fabric is nearly upholstery weight. Oh and I don't think I mentioned this anywhere but a WALKING FOOT IS A MUST, seriously don't try it w/o a walking stitch.
Showing the individual pieces
Trimming the joining edges
Folding over the 1/4 seam on one long edge of the FRONT sashing
Pinning the quilted piece front and back sashing all raw edges
The 1/4 inch seam through all layers
Folding and pressing the back sashing up while keeping the front sashing back and out of the way.
Just another view for clarity (hopefully)
Back of the next quilted piece to the back sashing right sides together pin in place
The seam sewn, all seams pressed towards the sashing, back is now one piece.
inserting the sashing batting into the sashing inside the seams for no added bulk
fold over front sashing matching folded edge to seam stitching line, pin matching points. This seam needs to be top stitched, the other side doesn't NEED it but I generally sew both for continuity. It will need some quilting since the batting isn't stitched in yet.
Here is the back
and the front.