You can’t overrule an inheritance law by adding some preference. Maybe in the USA, but in many country’s you can’t even write your children off their rightful inheritance.
In Germany you can deny them specific property, as the minimum share (Pflichtteil) only goes as far as monetary value goes, not some specific item. I.e., as long as you have over 50% of your net worth in the form of money, you are free to prevent your normal heirs/family from getting any physical assets you posessed.
But that's not what the parent poster asked for...