Sorry, just noticed your comment.
I don't think the city and neighbourhood generators will be merged (not anytime soon anyway) but while working on both of them I try to transplant ideas and solutions which seem good from one to another. I am going to remake districts in the city generator and it will probably become possible to "open" them in the neighbourhood generator (similar to opening towns and dungeons from Perilous Shores).
In the next update of this generator I am planning to make it possible to specify the neighbourhood outline by manually drawing it. That's not exactly what you are asking about, but somewhat close.