Is it possible to concatenate arrays?

Question

PHP

Is it possible to combine the contents of the arrays, if the key is already in use - then nothing, and if not - then you need to add from other arrays, but with an empty value

array(3) {
  [0]=>
        array(4) {
          ["attributes_3_ru-ru"] => "10"
          ["attributes_3_en-gb"] => "100"
          ["attributes_4_en-gb"] => "2222"
          ["attributes_4_ru-ru"] => ""
        }
  [1]=>
        array(2) {
          ["attributes_6_ru-ru"] => "10"
          ["attributes_6_en-gb"] => "100"
        }
    }
  [2]=>
        array(2) {
          ["attributes_4_ru-ru"] => "10"
          ["attributes_4_en-gb"] => "100"
        }
        ...n
}

What would be the output something like this

array(3) {
  [0]=>
        array(4) {
          ["attributes_3_ru-ru"] => "10"
          ["attributes_3_en-gb"] => "100"
          ["attributes_4_en-gb"] => "2222"
          ["attributes_4_ru-ru"] => ""
          ["attributes_6_ru-ru"] => ""
          ["attributes_6_en-gb"] => ""
        }
  [1]=>
        array(2) {
          ["attributes_6_ru-ru"] => "10"
          ["attributes_6_en-gb"] => "100"
          ["attributes_3_ru-ru"] => ""
          ["attributes_3_en-gb"] => ""
          ["attributes_4_en-gb"] => ""
          ["attributes_4_ru-ru"] => ""
        }
    }
  [2]=>
        array(2) {
          ["attributes_4_ru-ru"] => "10"
          ["attributes_4_en-gb"] => "100"
          ["attributes_6_ru-ru"] => ""
          ["attributes_6_en-gb"] => ""
          ["attributes_3_ru-ru"] => ""
          ["attributes_3_en-gb"] => ""
        }
        ...n
}

Answer 1

Addition of arrays.
$array_one + $array_two...

Answer 2

$arr_finished = $arr1 + $arr2 + $arr3 + ...
$arr_finished = array_walk($arr_finished, function(&$v, $k) {
    $v = isset($arr1[$k]) ? $arr1[$k] : "";
});