The wording "reflection-related" might be misleading. We should change the wording from "B is reflection-related to A" to something like "B reflection-forms A".
And in 10.1.7.6/5:
The alias D::Y is reflection-related to ::X, but not to B::Y or B::X.
The statement may be wrong IMO. And it should be replaced by
The entity ::X, but not alias B::Y or B::X, is reflection-related to D::Y.
or
The entity ::X, but not alias B::Y or B::X, reflection-forms D::Y.