Plus Aiki implying a mixing of Ki or mixing of ki strength . Who said that? Is that a personal view, an internal arts view?
It's an ancient and commonly used concept, Graham. While it's a revelation to most westerners, the concept of blending/mixing/combining with an opponent's "ki", it's a concept that has been around thousands of years. Reading the classics and being around Asian martial arts, Ueshiba would well have been acquainted with the term/idea. What's interesting is that once you understand the concept and think "Voila!", you begin to look around and say, "wait a minute.... I wonder if the old translation of 'using the opponent's strength' may have been more to the point of what they were saying?". In other words, there were lots of giveaways like "kuzushi" and "using the opponent's strength", but we all took them to mean the physical stuff that we could relate to in our own ignorance.