Pack dimensions

We can provide item dimensions when shipping multiple items in a single pack. With weight, SW correctly adds the weights. But with w/l/h, I would like to provide an entire pack's dimensions from my ERP system.

So item 1 - 5 lbs, 5 x 6 x 7, Item 2 - 3 lbs, 14 x 20 x 40. I would like to provide details in the xml, that would show - total pack - 8 lbs and 14 x 20 x 47 (or whatever), so that single scan can work on a single pack.