Simple AHK Script

Very simple to increase functionality of an application. I activate one of 48 windows by using ctrl-g, type the number of the window, and then enter. Two screens, so two windows open at any time, so 1 and 2, 3 and 4 ... etc I have coded this myself and it is fine, I can toggle between the windows easy. At 1,2 and I press down, I go back to 47,48 and vice versa when I press up. However I also need a triplet function included here. So if I press a button, code should read where I am and go to the next set of windows. Triplets are divided into (1,2..3,4..5,6), (7,8..9,10..11,12)... etc all the way to 48. If I am in the first, second or third set of windows, and I go up or down, it must correspond to the same part of the sequence on the next set. I.e. if I am in 3,4 and go up, it should go to 9,10. If I went down it would have gone to 45,46, etc