Use bucket in water elemental and get water

[Misterion]

So, I wish to make a system where I use an item on a creature and I get this item full of water, like a bucket in a water elemental, for example, or a bucket in a wolf where I get his milk.

But all I can do is use item on non creature objects. How am I supposed to use an item on a creature? And which function would be to change the empty bucket to a full of water bucket?

THE FORGOTTEN SERVER 8.6 0.3.6

 

[ond]

function onUse(cid, item, fromPosition, itemEx, toPosition)

    local source = {
        ["water elemental"] = {value = 1},
        ["vampire"] = {value = 2},
    }
   
    local v = source[getCreatureName(itemEx.uid):lower()]

    if itemEx.uid == getCreatureByName(v) and isMonster(itemEx.uid) and item.type < 1 then
        doChangeTypeItem(item.uid, v.value)
    end
   
    return true
end