He's wrong, as you were in the other thread.
(i.e. "Flare and I went to the park.")
That's an example of a grammatically relevant context of his statement. Mine was not. "You, Charles and I" is not correct.
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That's the entire point, the parties are there, therefore "[person] and I" isn't suitable. There are 3 people, not 2.
This is basic English that I thought Artificial, let alone LG would understand.
This sentence is also correct for the same reason the other one was correct.
Go say "you, Fred and I" to your English teacher and see if you don't get a slap directly in the face.