Mamagus,
Wonderful idea! esp. the book!
Not sure of any help here... bordering each of the fabrics with one or two thinner borders was my first thought, but perhaps Attic Windows is a good showcase for the lights/mediums and darks of the blacks. Another is to use BowTie to "tie" it together in every other block perhaps? and... last idea: what state are you/she from?... tho' I'm thinking you're out of the USA... perhaps alternating blocks of your state, or province or county, etc. would help bring "home" to the black fabrics. Those state blocks can be found if you google "state quilt blocks".
Anything would be striking with black as the "accent".
Best wishes to you and your project and to your dear Erin!