I made a major error in my previous post. I wrote:
But a common-sense reading of this suggests intuitively that the church in P&A's house is a subset or partial overlap of the people he is greeting and has written this letter to.
When I should have written:
But a common-sense reading of this suggests intuitively that the church in P&A's house is in addition to or a partial overlap of the people he is greeting, or a subset of the people he has written this letter to.
I've changed the original post to reflect what I meant to say