Keep in mind that most board visitors don't browse through a board--they do a SEARCH and generally they do a search of ALL boards and often use the advanced search options...that is where someone searching from ANY board will find posts on ANY OTHER board if they enter surnames in the surname box search. So, in that regard, the searches on surnames ARE connected to the surnames boards and every board in the system.
PS: The surname box is MOST useful in a search when an every word search wouldn't be productive...for example, when a very common surname that can be a common word, given name, etc. is the one you are looking for. The surname box searches are probably the only way to search for Joseph, List, Field, Cousin, James <---when these are SURNAMES you want to search. This means in these cases it is also most important when you post to USE the surname box.