I agree, dont wash until they are quilted. Once that is done, if the fabrics are stable, you can soak them in Oxi Clean.
Oxi Clean will take out the yellowing and most other age stains.
Mold will probably not come out, but the Oxi Clean will help to lighten the stains a little.
When I say soak, I mean soak. At least overnight and maybe even longer, but it will eventually remove the stains.
That said, You must be sure that the fabric is stable and colorfast. Post a picture of your tops and we can give you better advice.