I hope your visist turns out okay.

My FIL and his wife are monsters in public. He's the guy that thinks he's funny when he really comes across as a jerk. He and his wife yell at people they think are stupid and bicker back and forth. After the last incident, I told him and his wife to leave and never come back.

When they come visit you, your house, your rules, even if they are family. If it gets loud you could say, "Dad, could you talk a little softer please, it's hard to understand you when you talk so loud and when you keep correcting each other"

Yeah..get the public places, hence my FIL and his wife not coming back. Hang back and pretend not to know who they are. Once when he went to a Taco Bell and exclaimed, "Look! They have real Mexicans working here!" I refused to eat the food claiming I didn't like tacos. And that's a mild public visit.

If they love to talk, get them talking about family stories with his parents/siblings and hers. It's a great way to get to know them better. It was hilarious talking to my mom the last visit and she admitted she saw the old Yogi Bear movie my kids were watching in the movie theater when she was a kid. It was "wow..my mom likes cartoons??"