"Yin and yang" is Chinese. Ueshiba was speaking Japanese and would have said "In yo". "Ho" just means "method".
In and yo appear all through Ueshiba's writings - including the ones after he said that he had found "true budo". Also all of the other bits that Dan mentions. All of that is available in publicly available works.
Here's an interesting fact - Ueshiba wrote a commentary about how to do kokyu-ho, and one well known translation has it as "put ki energy into your fingertips" - only the original Japanese says "put power (力) into your fingertips". Do you begin to see the problem?
You mentioned "eight powers" in a previous post. OK, I'll bite - what are the eight powers, what do they mean, and where do they come from?
O.K. Chris, thanks for the clarification. So in English he said yin and yang. Yes, and my not knowing the Japanese translation led me to assume that was an add on. For this I apologise and stand corrected.
Many things appear all through his writings so I fail to see the significance there.
Yes Chris I do see the problem and have for many years.
The eight powers? I have a feeling you already know so why do you ask?