public GameObject AddLoot
{
set
{
    this.Loot.Add(value);
    AddLootItem(value);
}
}

// And then we have some call site:
muh_obj.AddLoot = some_loot;

// delete the property stuff
public GameObject AddLoot
{
    this.Loot.Add(value);
    AddLootItem(value);
}

// But we want to have a parameter
public GameObject AddLoot(GameObject value)
{
    this.Loot.Add(value);
    AddLootItem(value);
}

// OK we gucci fam
// Let's change the callsite.
muh_obj.AddLoot(some_loot);

// PogChamp we r done :)