Quilt conservationists always try to preserve a quilt maker's original work when doing a repair job, and the most popular "fix" for a crazy quilt with shattered silk patchwork is to applique a piece of lace over the shreds of the old patch. A lot of us joke that this is just making a net bag for the old silk to collect in, but it does contain the damage and preserve the original fabric.
Note: you should not attempt to restore any antique quilt before you have it professionally evaluated and appraised by a quilt restorer or conservationist. However, if you have an old crazy quilt laying around the house that is only of sentimental value, or find a piece on eBay or at a rummage sale that you want to play with, this can be a fun project.
Most of the yardage lace I buy is pure white so I can dye it myself to match a project (old dressmaker's trick.) For old quilts I usually tea- or coffee-stain the lace to give it an aged appearance more in keeping with the antique piece.
To tea stain lace, first cut the amount you intend to use, then immerse it in lukewarm tea made from tea leaves or bags and water (I let mine soak at least 45 minutes; the longer it soaks, the darker it will stain.)
Most teas will stain lace and other light fabrics with a soft golden look so many old fabrics acquire over time. This is called "yellowing" just as with pages in old books. Regular coffee, on the other hand, turns white lace more of a taupe color, like true ivory (and you can use leftover coffee to stain lace; I usually save and reheat whatever my guy doesn't drink in the morning.) If you're not sure which you'd like to employ, experiment with both and see which you like best.
Here's the stained lace against my white marble cutting board:
I use silk thread to do most of the repairs on silk crazy quilts. It's expensive (I use Gutterman, which runs about $5 per hundred yards spooled) but nothing glides as cleanly through the old fabric unless you wax it, and I hate the residue waxed thread leaves behind. Also, if you want you can tea-dye silk thread to match your lace.
If you have a finished edge to your lace, you don't have to turn it under before you apply the patch (see mine next to the dark blue velvet patch below.) Because seams show through lace repair patches, you should keep the edges you turn under modest; if possible no more than 1/4". Also, the busier the pattern of the lace is, the more you're likely to notice the edges that are turned under:
Next up: repairing with harvested patchwork.