Thanks Jim I can see the error now, it has been driving me crazy !!! This is a great information resource, I have learnt so much from it. The biggest revelation for me was the small number of crossovers on average per chromosome. I am wrestling with that and the information you provided to work through the overlap logic to highlight the crossovers between 3 first cousins and one niece, daughter of a fourth first cousin all from the paternal line. In particular if 3 or 4 cousins line up at a specific position I assume it follows that since they all have that transition it must be an established crossover point from a common descendent, at least their grandparent but could be earlier. Thanks again for helping out above.