My struggle was this: These passages quote God's promise, which is basically the one that appears in II Samuel 7. Yet, the exact phrase in those passages does not appear in II Samuel 7. So are these passages referring to II Samuel 7, or to an independent tradition?
One thing I noted was that quotations can be loose. We see this in I Kings 8:25, which expands on the phrase that appears in I Kings 2:4 and 9:5, while claiming to quote God.
But, in a sense, the solution to my problem was staring me in the face without me realizing it. I Kings 8:16-21 is presented as a direct quote of God, specifically of the scene in II Samuel 7. Yet, it's different from II Samuel 7, since it subordinates that chapter to a Deuteronomic agenda. I Kings 8:16-21 has different emphases and a slightly different order from II Samuel 7. And yet, there are similarities in vocabulary, word-order, and phrases between I Kings 8:16-21 and II Samuel 7, as I show in I Kings 8's Allusion to II Samuel 7 and I Kings 8's Allusion to II Samuel 7, Part II. Consequently, I think that I Kings 8:16-21 is alluding to II Samuel 7, even if it doesn't quote it exactly.
But there are times when I Kings 8 claims to quote God's revelation to David in the story that appears in II Samuel 7, yet it refers to ideas that are not explicitly in II Samuel 7. In I Kings 8:25, Solomon quotes God saying to David, "There shall never fail you a successor before me to sit on the throne of Israel, if only your children look to their way, to walk before me as you have walked before me." I Kings 8:25 says that God's promise to David of a lasting dynasty was conditional on obedience, whereas II Samuel 7 presents it as clearly unconditional.
What can one do with this? Does the person who added the conditionality believe that God gave David that condition, only it didn't appear in the text of II Samuel 7? Or is he reading the condition into II Samuel 7, since David feels a need to ask God to fulfill his promise in II Samuel 7:29, possibly implying it's not totally certain?