It might depend on how "fiddly" your quilt design is but if you are using enough straight lines, can you put the stencil where you want to mark, placing straight pins upright where you'd usually do marking? Then stitch from one pin to the next, removing them as you go.
As to washing, If those sat for a long time, the finished quilt may benefit from a gentle wash. I don't know that I'd put it in the machine but perhaps in the bath tub and squishing water through it and then put it through a spin cycle in the washer to get the rest of the water out. I recently finished and hand quilted a very old top. It did fine and the laundry brightened it up that it looks--and smells--"new" again.
If these were blocks and you've handled them putting them together, you know the integrity of the fabric at this time. If they've done well with being constructed into a top, they probably will do ok in getting a bath. Just be gentle.
Last edited by illinois; 12-21-2023 at 04:47 AM.