Relative adverbs

I am having some trouble understanding why relative adverbs function as adverbs in a relative clause.

My family worships in a church, where my parents married.

In the above example, I understand "where my parents married functions as an adjective clause, but cannot comprehend how where modifies the verb married.

A relative form is a pointer to some other constituent in a sentence. When a relative is employed, as here, in a bound relative clause, it points in two directions, toward an explicit constituent in the head clause and toward a missing constituent in the subordinate relative clause, and signifies that they are the same entity.

  This is [the dragon] which George killed [_].  
              ↑        ↵↳                  ↑

In other words, "This is the dragon. George killed the dragon. The two dragons are the same dragon."

Where is a 'pro-locative': it points to a locative expression in the same way that who, a pro-noun, points to a noun phrase. Since most locative expressions are preposition phrases (PP), where may usually be understood as a 'pro-PP', equivalent to PREP which. As a relative it points to an explicit placename in the head clause and to a missing preposition phrase in the relative clause. The only tricky part is figuring out which preposition is intended.

 My family worships in [a church] where my parents married [_].
                          ↑        ↵↳                      ↑

In other words, "My family worships in a church. My parents married in a church. The two churches are the same church."

"Where, when, why" can be used in relative clauses as in "the church where my parents married". In this use they are often called relative adverbs, but the Longman English Grammar uses no name at all. The term adverb is perhaps not optimal. Here it does not mean that "where/when/why" modify a verb as an adverb of manner. The primary function is to connect the relative clause to the noun before. Perhaps we should or you should invent another term, if you have problems with adverb. You might say "relative connector", to make the function of the three words clearer. We have to live with the fact that not every traditional grammar term is optimal.

"The church where my parents married" is the same as "the church in which my parents married".