the will only gets so far. for example there have been cases where children of a family have completely abandoned their parent/s, and a 3rd part good samaritan came along to help said person for years before their eventual death, and the will gave the inheritance to the good Samaritan, which causes the blood children to object.

the only clearcut way is to have the parties in attendance while the will is being written so that any objections wpuld get aired out while said person is alive and can make the call

As the article mentioned, wills are often contested. The cases they presented were all from people with wills, but the surviving parties didn't accept what the got in the will.