How do I insert data from a form to multiple tab

//this is the main
include('database.php');
 include ('functions.php');

   if(isset($_POST['save']))
   {
       $name = mysqli_real_escape_string($con,$_POST['name']);
       $surname = mysqli_real_escape_string($con,$_POST['surname']);
       $phone = mysqli_real_escape_string($con,$_POST['phone']);
       $email = mysqli_real_escape_string($con,$_POST['email']);
       $address = mysqli_real_escape_string($con,$_POST['address']);
       $sn = mysqli_real_escape_string($con,$_POST['sn']);
       $inv = mysqli_real_escape_string($con,$_POST['inv']);
       $reseller = mysqli_real_escape_string($con,$_POST['reseller']);
       $price = mysqli_real_escape_string($con,$_POST['price']);
       $tbPrice = mysqli_real_escape_string($con,$_POST['oprice']);
       $resdate = mysqli_real_escape_string($con,$_POST['rdate']);
       $tbDate = mysqli_real_escape_string($con,$_POST['tdate']);
       $itemName = mysqli_real_escape_string($con,$_POST['item']);
      
      
       //calling function to run query
       multiquery($name,$surname,$phone,$email,$address,$sn,$tbPrice,$tbDate,$inv,$resdate,$itemName,$price,$reseller);
       
       
       /*insertClientInfo($name,$surname,$phone,$email,$address);
       
       InsertSales($sn,$tbPrice,$tbDate,$inv,$resdate);
       
       insertItem($sn,$itemName,$price);*/
       
   }

//this is the function


function multiquery($name,$surname,$phone,$email,$address,$sn,$thaboPrice,$thaboSoldDate,$invNum,$rsoldDate,$itemName,$price,$reseller)
{
    
    include('database.php');
    
    
    $sql = "INSERT INTO client(name,surname,phone,email,address) VALUES('$name','$surname','$phone','$email','$address');";
    $sql  =$sql ."INSERT INTO client_item(puch_id,client_id,serial_no,tb_price,t_date,res_date) VALUES($invNum,(SELECT client_id FROM client WHERE name ='$name'),'$sn',$thaboPrice,'$thaboSoldDate','$rsoldDate');";
     $sql = $sql ."INSERT INTO item(serial_no,item_name,price,Reseller_id) VALUES('$sn','$itemName',$price,(SELECT Reseller_id FROM reseller WHERE ResellerName ='$reseller'));";
     
     
     if(mysqli_multi_query($con,$sql))
     {
         echo "Successfuly INSERTED";
     }
     else{
         echo "Failed to insert info". mysqli_error($con);
     }
}