Keep a family disagreement small enough that people are not forced to recruit sides.

Disputes grow when they start collecting supporters. What begins as two people disagreeing about a weekend becomes a matter on which cousins have positions, and once others are involved everyone has an audience to lose face in front of, which makes retreat far more expensive than it was. The recruiting, not the original disagreement, is usually what does the damage.

Keep the conversation with the person you actually disagree with. Resist the call that begins with wanting to check whether you are being unreasonable. If someone tries to enlist you into a quarrel that is not yours, you can listen kindly without agreeing to hold a side.