Yes I did search it, and also found the example file, which proved useful in creating one nomograph. I am out of my depth here, because I don't have the formula for the graphs, and assuming a 45 degree slope is incorrect. Apart from physically measuring the slope, I've set up "known" solutions. I however, have no idea on how to combine separate nomographs to produce a result, shown on my first message.
(I'm one of those self-taught Excel users and have a bare bones grip on VBA. Other than that, I'm relatively useless in comparison to other users on this forum. Any help or advice is appreciated!)