Look , it's IMPOSSIBLE WITH SCRIPT
but i think it's possible with C++
if(item->isStackable() && toItem)
{
uint32_t m = std::min((uint32_t)item->getItemCount(), maxQueryCount), n = 0;
if(toItem->getID() == item->getID())
{
n = std::min((uint32_t)100 - toItem->getItemCount(), m);