Good point would fit and make Aqua's story more of a backbone of the whole thing.I like your theory, although I would merge 0.2 and kh3 instead as one is the prologue of the other. The whole kh3 journey is to find where Aqua is (mostly). Showing her struggle in the same game would make the reunion much more impactful.
In that case the BBS DLC would simply contain the plozpoints of Re:Coded and DDD. Like maybe instead of having to search the datascape for Namine's message, they look for it in the dreamworlds?