Can you give us some other examples of these last two compounds so we can detect a pattern? Do the possessive compounds have to be hyphenated, for example? Since the copulative compound is a simple word, such as pair, could the possessive compound also be a simple word such as bushel?

I'm at work now, so am away from my reference library, but an example of dvandva would be: Ramasitau. Rama is one of the incarnations of Vishnu, and the eponymous hero of the Ramayana. His wife's name is Sita. Ramasitau means in Sanskrit Rama and Sita (together as husband and wife). An aside is that the ending -au is the dual (not plural) nominative. I can't think of an English example, but in Sanskrit, you can put two nouns together into a compound word. No 'and' or 'or' conjunction necessary. Bahuvrihi is an example of itself. It can be used as an adjective meaning 'possessing a lot of rice' hence rich. You could say something like Jheem bahuvrihi meaning Jheem who possesses a lot of rice. Not that Jheem is a noun and bahuvrihi is an compound adjective in this example.

I was saying that most collocations are compounds. Whether the compound has a space like crystal clear, a hyphen like high-fiber, or nothing like honeymoon. (I'd argue that that's just an orthographic convention in English.) And dvandva and bahuvrihi are just linguistic terms that Indian grammarians came up with, but which linguists still use for languages other than Sanskrit.

Hope this helps.