Breakdown of Завтра я посмотрю запись о браке, копия которой была там.
там
there
я
I
о
about (о, об, обо)
быть
to be
Questions & Answers about Завтра я посмотрю запись о браке, копия которой была там.
Why is которой in the feminine Genitive form here?
Которой means "of which" in this sentence. It is feminine because it refers back to the feminine noun запись (record). It is in the Genitive case because it shows possession, exactly like saying "a copy of the record".
Why does которой come after копия (копия которой) instead of at the very start of the clause?
When который is in the Genitive case to mean "of which" or "whose", it usually comes right after the noun it possesses. Instead of saying "of which a copy was there", the natural Russian phrasing is копия которой (copy of which).
Doesn't the verb посмотрю require the Accusative case? Why does запись look like a dictionary form?
It actually is in the Accusative case! Запись is a feminine noun ending in a soft sign (-ь). For this specific group of nouns, their Accusative form is identical to their Nominative (dictionary) form.
Why does the word for marriage (брак) have an -е at the end?
The preposition о (meaning "about") forces the following noun into the Prepositional case. For a standard masculine noun like брак, you form the Prepositional by adding an -е to the end, making it о браке.