If you want some deep background on the politics on Boston MA, you will soon encounter James Michael Curley, the legendary Boston politician that dominated Massachusetts politics in the first third of the twentieth century.
Here are two good sources about this flamboyant politician. "The Rascal King: The Life and Times of James Michael Curley" by Jack Beatty. This large book was offered by the History Book Club, when it was published in 1992. I read it twenty years ago and remember it deals with the intricate nature of Boston ward politics, although I do not remember if it answers your very specific questions.
A much shorter and more recent book is "James Michael Curley: A Short Biography and Personal Reminiscences" by William M Bulger. Billy Bulger dominated the Democratic Party and the Massachusetts state senate in the fourth quarter of the twentieth century. Then he became the president of the University of Massachusetts and surprised his many critics by becoming a scholar of some renown. In fact, Billy Bulger probably has written a book or scholarly article that will answer your very specific questions about the finer details of Boston Ward borders.