For box calculations I model a single driver and then multiple the individual single box by the number of drivers in the array. For instance for a 10 mid woofers box you would need to multiple by 10 to get the size of the large box. Now that would be easy for a sealed box but what I do is to segment the large enclosure so that only a few drivers are in each smaller box. The individual segments effectively add bracing which is usually a good thing. For a vented box just compute the venting for the segmented box. For my Needles I used 4 segmented boxes which enclosed 4 drivers each. Some software like BassBox Pro will compute multiple paralleled drivers in a box but that wouldn't cover all cases for arrays.

You can use techniques in my white paper to compute the overall SPL and impedance when you series/parallel the drivers.

Jim