php - Append array into multidimensional array using key -

i've 2 multidimensional arrays , need merge both specific key. tried array_merge_recursive , array_search poor results.

so,

main arrays:

 array (     [group] => array         (             [subgroup] => array                 (                     [items] => array                         (                             [item 1] => web development                             [item 2] => dba                             [item 3] => qa                         )                 )         ) )  /* ------------ */  array (         [item 1] =>  array             (                 [user 1] => array                     (                         [properties] => array                             (                                 [id] => conexion_1624                                 [name] => jhon doe                              )                     )                 [user 2] => array                     (                         [properties] => array                             (                                 [id] => conexion_2001                                 [name] => alice , bob                             )                     )             )     ) 

expected result:

 array (     [group] => array         (             [subgroup] => array                 (                     [items] => array                         (                             [item 1] => array                                 (                                     [user 1] => array                                         (                                             [properties] => array                                                 (                                                     [id] => conexion_1624                                                     [name] => jhon doe                                                   )                                         )                                     [user 2] => array                                         (                                             [properties] => array                                                 (                                                     [id] => conexion_2001                                                     [name] => alice , bob                                                 )                                         )                                 )                             [item 2] => dba                             [item 3] => qa                         )                 )         ) ) 

if arrays structures not changed

foreach($the2nd $key => $item)    $the1st['group']['subgroup']['items'][$key] = $item; 

update due discussion in comments

if in 1st array items may not on same level, such code find them

array_walk_recursive (       $the1nd ,       function($v, $k, $the2nd) { if(isset($the2nd[$k])) $v = $the2nd[$k]; },      $the2nd);