Examples:

Ubi amor ibi fides — Where there is love, there is faith

Ubi Libertas, ibi patria — Where liberty is there is my country

Here is a helpful link to more great family mottos.

Or, why not have some fun and make up your own?

Death before Discretion (for the gossips among us!)

Virtue is More Powerful than Gold… but Sin is a lot more Fun!