public static void AddToOwnedProducts(Product product) { if (ownedProducts.Exists(x => x.Name == product.Name)) { ownedProducts.Find(x => x.Name == product.Name).Amount += 1; } else { Product p = product.ShallowCopy(); ownedProducts.Add(p); ownedProducts.Find(x => x.Name == product.Name).Amount = 1; ownedProducts.Find(x => x.Name == product.Name).Id = _counter; _counter++; } }