Discussion Forum—A Way with Words, a fun radio show and podcast about language

A nitpick: I don't think #1 is clumsy, but there's one way in which it differs in meaning from the rest:   "My friends" means not "some friends of me" but "the friends of me".   So technically "my friends' friends" means "the friends of my friends".   #1 really has to be "some of my friends' friends", to be picky about it, and then it does begin to sound clumsy.

(Kudos, by the way, on ruling that #3 is not actually wrong.)

I like 1) or 2) in this case. I am personally confounded with coming up with a rule as to when to use the subjective or the possessive in example 3), but I affirm that in most cases you can use either. I would not understand example 4) to mean "friends of my friends" if I saw it. In fact, it looks to me like a typo of "friends of mine." I don't think you can add a possessive ending to "mine" forming "mine's" -- unless of course you mean "mine" as a source of raw ore. Example 5) seems awkward, but could have a useful nuance of affirming that you know these second-degree friends.

Back on the topic of example 3) refer to the previous thread in which my confusion is quite manifest:
1) Admit we were possessive and that our language has become unmanageable

Some day I will have to do some legitimate research on this topic.