Well, Ueshiba did sometimes use the term "harmonize", but much more often that's a mistranslation of the kanji for "Ai", which doesn't really mean "harmonize" in the sense that native English speakers usually use it.
Actually, Chris, "combine" is perfect for what he meant. Or "vector addition". The problem becomes, as you can see, that the intention of the words is often very clean, but the knowledge of the translator is often very sparse. Once a translator understands the gist of jin/kokyu, a lot of these seeming mysteries boil down not to the "hidden secrets", but to the translator's lack of background.