I don't remember where I learned this, probably at the Quilting and Sewing Expo but this is what I learned -
If you can't match a fabric for a repair you can scan it, duplicate the file and put the pictures together on the computer in a graphics program, making a larger piece. Then you print it onto fabric made for ink jet printers and use the resulting "fabric" for the repairs.
Not sure if this idea will help, but thought I would share anyway. I thought it was a really creative solution to repair an old quilt.
Love, Jann