If I am understanding your original post correctly -

You want to attach the top by stitching only partially through the wadding/batting and do not want the stitches to show on the back

and

you also want to attach the back to the same wadding/batting by only stitching partway through through so the stitches will not show on the front??

If you want two quilted designs, I am thinking it would be almost easier to make two quilts and just stitch through all three layers at one time on each of them.

I had planned to do a pattern of hearts on the back, but if I have to stitch through the front too then I would have to do squares, that's all! The front is a completely rainbow patchwork of squares, so any other shape of quilting will create lines across them that will spoil the effect of the squares because it wouldn't be possible to use an invisible colour of thread. I can do squares "stitched in the dip" if necessary, and forget about the hearts/ embroider some hearts instead.

Alternatively, it looks as though my great uncle's quilt has a new, unquilted back sewn over the original quilted one, which works, and I was wondering if I could perhaps get one of those ready quilted backings and quilt it to the back in the heart pattern, then sew the front over the ready-quilted bit, with a few strategically placed stitches to stop it flapping...

I found this article quite informative and helpful. http://www.hobbsbatting.com/resource...k5ZlkifQ%3D%3D

There are so many battings out there that it is hard to decide. Hopefully it will be usesful as a reference.

You could stitch your hearts by just quilting the backing to the wadding. Then put the top onto the already quilted backing and wadding and stitch in the ditch to join all three layers. The back will show the squares from stitching in the ditch but the top will not show any stitching.

I have done this the other way around by quilting the top/wadding together and then laying it on top of the backing and joined with sitd.

My favorite and I have used in lots and lots of quilts is = high loft polyester batting. Warmth without the weight. I do mostly FMQ so no bunching or lumpiness after many, many washing and dryings.

People on here will tell you their favorite kind, so it will be up to you to use what you want and like.

Wow, more to think about, but definitely useful, thanks!

I think I've been told that already... this is the point where I live up to my chosen username and realise that the actual problem is not the same as the apparent problem here. The actual problems are:

a) Having googled quilt wadding instead of making it up as I went along like we did back in the 00's before the internet took over, I have realised that my previous quilts are held together by a mixture of optimism, geometry and shite polyester batting, and that if I want to make a proper quilt it is going to involve a lot more sewing.

b) This means that if I do this properly there is absolutely no way it will be ready in time for my friend's wedding.

c) Having experienced the heavy wool quilt and the stiff polyester quilt that are shoved in cupboards, and the fluffy polyester quilt that is constantly in use, I am instinctively aware that batting is really important but having never experienced the fancier varieties I have not the foggiest idea what they are actually like.

The solutions:
1) Quilt this properly, using the method suggested by JanieW where I quilt the hearts into just the batting and backing first and then the SITD squares through the whole thing. Then I just need to make sure I get something with a maximum sewing distance of at least 4" (my square size) and labelled as "machine washable" "suitable for hand sewing" and it should be fine! (Oh drat, it looks like the ones that are best for hand sewing are wool... but I've had an entire felt dragon turn to powder before and can't face that again. And the ones I had my eye on (warm and natural and heirloom 100% cotton) are apparently rather stiff to sew by hand. Hmm). I wonder if I could get away with quilting the back, then washing it so it goes a bit crinkly, then quilting on the front after it's shrunk so the squares stand out less?

2) Accept that the quilt won't be finished by the wedding, but that I will probably be able to get it to at or near the stage I thought was finished, so I can give it half-finished so they can see what it's like and explain that I'll need another month or so to sew the squares in (and add the binding, which presumably comes after that).

3) Go to a real-life fabric shop and poke stuff to see what feels right.

Does that sound like a plan? Thanks everyone!

Maybe start with #3 - go to the fabric shop and check out the new battings/waddings?

(Although here in the USA, sometimes they are folded up and tightly wrapped in plastic - but the shop(s) may have small samples that you can touch and scrunch.)

I have to agree with the suggestion to use flannel whole cloth as an alternative.

(in the UK, look for a superking brushed cotton flat sheet or even a brushed cotton duvet cover that you can cut apart.)

Quality Flannel/brushed cotton has become my default batting material. It’s cozy, it’s warm. It’s wonderfully cuddly. It takes a hot cotton wash without any issues. And because it is woven fabric instead of traditional batting, you don’t have the stability issues or quilting distance requirements some battings need.

It would be be helpful if we could see a picture of your quilt top, to make suggestions on the actual quilting pattern.

I can take a picture later, but the gist is: very simple but very big patchwork of squares. The squares are all different colors and in a normal boring grid. They are 4" and there are 18 to a side, so the quilt is (about) 6".