"collaboration among" or "collaboration between"

I have seen “between” vs. “among” and am aware of the possible duplicate nature of my question. My point here, however, is specifically to find out what it should be in conjunction with 'collaboration'.

As you may see on the last page of the Grammar Girl source in the highest voted answer to that question (http://www.quickanddirtytips.com/education/grammar/between-versus-among?page=2) there are several training sentences. One is:

The conversation [between/among/either] the teachers, the parents, and the students lasted for two hours.
[Answer: between]

If the answer here is between, my hunch is that collaboration should also be 'between' any number of people. My friend, however, vehemently disagrees with me and says "among should be used when there's more than 2".

What do you think, and why?

My sentence:

The successful collaboration among/between the contractors, the LA municipal office, and the funding provider resulted in reduced cost and higher efficiency.

Solution 1:

The correct answer: "The successful collaboration between the contractors, the LA municipal office, and the funding provider resulted in reduced cost and higher efficiency."

Using between or among in conjunction with collaboration doesn't change the usage.

Your sentence draws a direct relationship between the specific parties, so use between.

To clarify further, you would use among if the sentence read, "The collaboration among invested parties resulted in reduced cost and higher efficiency."

You might find it helpful in the future to visualize your sentences as sketches.

The sentence with between: a picture with lines drawn between the parties. The relationship is defined.

The sentence with among: a dotted circle around the parties, lumping them together. Collaboration exists somewhere in that dotted circle but it's more ambiguous.

Solution 2:

In my experience, and in regards to the next 10 sites returned by Google, Grammar Girl seems to be completely out of touch on this one.

Additionally, if you are reading or writing legalese, there appears to be a technical distinction between the two words more rigid than that in common speech: Between vs. Among