Write a setter function for each of the variables to set the other two.
I think something like this would work (though I wonder if you meant to have the value of Three to depend on One and Two, not One and Three):
UPROPERTY(BlueprintSetter = SetTwo)
int Two;
UFUNCTION(BlueprintSetter)
void SetTwo(int Value)
{
Two = Value;
Three = One / Three;
}