Action hook between the first and the second FPU row

something_1_2_fpu_row.php

$n_match = 0;
function fp_action(){
  global $n_match;
  $n_match++;
  ob_start();
    do_action("__between_fp_rows_{$n_match}"); 
  $my_action = ob_get_contents();
  if (! $my_action ) return ''; 
  ob_end_clean();
  return $my_action;
}

add_filter('fpc_block_display', 'something_between_rows');
function something_between_rows( $_html ){
  return preg_replace_callback('%(</div>)(<div class=[\'|"]fpc-row-fluid)%', 'something_between_rows_callback', $_html);
}
function something_between_rows_callback( $matches ){
  return $matches[1] . fp_action() . $matches[2]; 
}