The developers mainly focused on implementing features that they themselves needed for scenarios and campaigns. In this case, battles with heroes fighting using physics were not something they "programmed," so it's quite possible that such a function doesn't exist. Reinforcements... Can't you find its ID? Judging by the IDs I see, it could be either 296 (it comes after 295, the last one in the list of battle cries). Or there might be a suspicious gap in the 240-276 range. But in general, it's a bit unclear here.