Any APA gurus available?

On a more serious note, I have a question for anyone who has better knowledge of APA style than I (this is a very large category of people, I suspect).

For reasons that will remain mysterious, my book was copyedited into APA style, and rather than have it turned back into MLA, I just went with it. But I'm coming across occasional issues in my MS, given my unfamiliarity with APA. For example, there are several points in the manuscript where I mention someone's reference of other work. For example, I might say that Scholar X builds on Scholar Y's idea of Z, where Z is a perspective or term that has been elaborated over a series of publications. I'm quoting Scholar X, and thus I need to include her in my bibliography and include the pub date in the text itself. I understand that.

But when it's a secondhand reference not to a specific text in the case of Scholar Y, but to one of their ideas that is being applied, adopted, transformed, or whatever in Scholar X's text, do I also need to include the inline parenthetical date for Scholar Y, and include their work in my bib as well?

I have to admit that this feels counter-intuitive to me, and yet, my copyeditor has entered the dreaded (xxxx) after each time I reference a proper name, without (it seems to me, at least) much sensitivity to the context of that proper name. But I'm hesitant to reject it out of hand, given the fact that I don't really know APA style at all, and my forays into the Publication Manual haven't yielded an answer.

Bottom line is that I can suck it up, and just track down the handful of citations that I'd need and include them in my bib--I may just do that anyway to reduce friction. But I am curious, because it's an element of my writing style that I don't think about often--I'm used to casually citing "common knowledge" sorts of ideas without imagining that I need to detail them formally.

Thanks ahead of time if you have an answer.