relative clauses - The way which you should hold them

The Cambridge Grammar of the english Language, page 224, reads

Complements are most often NPs, and conversely NPs are usually
complements. Some NPs can occur with adjunct function, but they tend
to belong to very restricted semantic types, mainly time or manner.

A distinctive property of such NPs is that they cannot be replaced by
personal pronouns:

They saw her then/*it, You should hold them so/*it.

Similarly there are no corresponding relatives with which: the way that/∗which you should hold them.

I do not understand the reason why the way which you should hold them is wrong, that is what relation "similarly" marks in the paragraph.