Bills and Chargers are already in the SOS. It appears like some posters falsely assume the Bills and Chargers will be added to the SOS formula after we play them which is incorrect. The math guys doing the SOS already know our schedule so all games/teams are included.
Having said that, every team's winning percentage changes weekly so the SOS changes weekly as well. For instance Buffalo is 11-3 right now so they have a 11/14 = 0.786 winning percentage. If Buffalo wins their last three games, the winning percentage would be 14/17 = 0.824. So the Pats SOS would increase, not a good thing, but not by a lot because the 0.038 increase is averaged over the whole 17 games. I am too tired to do all the math right now, I am not a math whiz, but you can see the Bills and Chargers winning is not doom and gloom. If the Bills lose 1 out of their last three games their winning percentage drops, 13/17 = 0.765, and helps our SOS.