I understand now have PMX works. But, say i have 7, 7, 1, 8, 1, 8, 9 ,9 ,7, 1, 1, 8 1, 1, 1, 8, 8, 7, 7, 9, 9, 1, 7, 8 and my crossover sites are: 7, 7, 1, 8, 1, | 8, 9 ,9, | 7, 1, 1, 8 1, 1, 1, 8, 8, | 7, 7, 9, | 9, 1, 7, 8 In the case of '7', how do decide which '7' to show and which to cover up, as in... 7, X, 1, 8, 1, | 7, 7, 9, | X, 1, 1, 8 1, 1, 1, 8, X, | 8, 9, 9, | X, 1, 7, X In the fist child, the first 7 is shown, not the second or third. But how do I know that it is this '7' that should be shown and not either the second or third occurence of 7? Cheers