Keep the focus on understanding the other person’s issues and perspective instead of on “winning” the battle. For fights you're not directly involved in, avoid donning the black and white-striped shirt to referee family members, and instead communicate how to fight fair from a place of experience. “Tell your children to give their partners a chance to express, and slow down, so it’s easier to repair a fight,” says Novell.
Another tip: It's best to keep an argument between blood relatives, instead of involving in-laws in the communication, whenever possible. If you're upset that your daughter’s and her husband have arrived late to the past several family gatherings, bring it up with your daughter—even if you have a sneaking suspicion the root of the problem is your son-in-law. “Often times family will overlook if a blood relative has said something hurtful, but the reality is, with non-blood relatives, bad feelings are more likely to simmer.”