Things get more interesting, however, when the Ravens play the Patriots, since the Schwartz sisters are both married to New England fans. And like the Schwartzes, the husbands are die-hard fans.
"There's that whole dynamic. It's just insane how many big games have come down to the Ravens and Patriots," Karin Schwartz said.
"It's great times. The whole family is together in one house, sometimes different rooms," Rich Schwartz said. "It's always great. A couple years ago in a playoff game in New England, we crushed them, so it was great for us. Then they had their year last year. We'll see who comes out ahead this year."
He's hoping for more than one reason it's the Ravens. If they win, he can take down the picture of him in his brother-in-law's house, the picture of him in a Rob Gronkowski jersey, that he signed "I love Tom Brady."
"I would love for that to come down this year," Rich Schwartz said.
Karin Schwartz said it's fun and irritating all at the same time to watch the game with Patriots fans.
"It's irritating in that Matt can turn any conversation to Tom Brady. You could be talking about tires, then suddenly it turns to Tom Brady," she said. "He does it now just because it annoys me."
Her brother-in-law always makes her somehow say something positive about the Patriots or negative about the Ravens.
"Then he'll nag at you until you tell him to shut up," she said.
She and her husband, Matt Desrosiers, will be watching the game on television with their son, Kyle, who sports Ravens wear, not Patriots (Schwartz had to agree to raise Kyle a Red Sox fan in exchange for the Ravens). Not that she'll be enjoying it.
If the Patriots are winning, Desrosiers will be gloating, Schwartz said. And if the Patriots win, and it's anything like last year, when the Ravens should have won, it's going to take her a while to get over it.
Rich Schwartz and his wife, Erin, and his sister, Kerr, and her husband, Chris, will be at the game in Foxboro Sunday.
"This is the rematch from last year. It's kind of that overtime period now that we finally have a kicker," he said. "I'm excited because it could be Ray's last game or, hopefully, an AFC Championship win. Either way it's a win for us."
"We've been privileged to see Ray's career throughout the years. He said this is last ride, and we're kind of taking it with him," Schwartz said.
As for a prediction, he won't be surprised if the Ravens are in New Orleans in a couple weeks.
If that's the case, Schwartz and his wife hope to be there, where the two met 10 years ago during the 2002 Super Bowl Mardi Gras celebration.