Magento only stores shipping address firstname on Paypal Express orders

> Magento and Paypal Express combine to have a difficulty with first and last names. So you end up with the shipping address only having the firstname filled in and the last name empty.
I did some research and found most of the answer herehttps://magento.stackexchange.com/questions/99884/paypal-express-firstname-and-lastname-instead-of-shiptoname, so thanks to https://magento.stackexchange.com/users/5288/loeffel.
It seems to be that Magento processes the response from Paypal the SHIPTONAME value being firstname lastname. In app/code/core/mage/Paypal/Model/Api/Nvp.php in the function _exportAddressses

$shippingAddress->addData(array(
     'firstname'  => $data['SHIPTONAME'],
));

Thats ok mostly but it causes some issues if your shipper requires lastname and firstname so can be a bit annoying.
So you can change it if you need to.

$nameParts = $this->splitNameIntoFirstAndLast($data['SHIPTONAME']);
$shippingAddress->addData(array(
     'firstname'  => $nameParts['firstname'],
     'lastname'  => $nameParts['lastname']
));

I've added a function splitNameIntoFirstAndLast to that file to split the name eg Colin Smith to 'firstname' = Colin, 'lastname' = Smith. I can write a function given the customers of the store that had this problem ok working out about 98% of them. Probably because the customers mostly have European names. I think you would have to rethink this if your customers were from different places say Chinese or Vietnamese for example.
The other file you have to change is app/code/core/mage/Paypal/Model/Express/Checkout.php which just comments out this line in the function returnFromPaypal which makes that lastname editable.

$shippingAddress->setLastname(null);

The function I wrote for splitting names looks like this. I think this is the bit you would want to change depending on your customers. I expect I'll tweak this over time.

function splitNameIntoFirstAndLast($originalName){
    $debug = true;
    /* if we have debug on we are testing and count failures
    * about 1.48% have empty last names in past 7308 with no last name in db
    */
    if($debug){
        global $count;
    }
    $titles = ['Dr','Dr.','Mrs','Mrs.','Mr','Mr.','Ms.', 'Ms', 'Miss.',
'Miss'];
   
    $name = trim($originalName);
    /* one bloke had name Colin Smith */
    $name = str_replace(' ',' ', $name);
    /* if the name begins with a . like '. colin smith' */;
    $name = preg_replace('/^\. /', '', $name);
    /* if the name ends with a . like 'colin smith.' */;
    $name = preg_replace('/\.$/', '', $name);
    /* replace multiple whitespaces with one people like
colin               smith */
    $name = preg_replace('/(\s){1,}/',' ', $name);
    if(strpos($name,',') !== false){
        /*
            if they enter their name with commas in then its probably
best to leave it,
            we could reverse it but its not always
            surname, firstname
        */
        //$name = trim(implode(' ', array_reverse(explode(',', $name))));
    }
    $foundTitle = $cofound = false;
    $nameParts = explode(' ', $name);
    /* colin smith C/O Some Company */
    if(stripos($name,'C/O') !== false){
        $nameParts = preg_split('/C\/O/i', $name);
        $nameParts[1] = substr($name, stripos($name,'C/O'),3).$nameParts[1];
        $cofound = true;
    }

    $currentNamePartIndex = 0;
    $firstName = $nameParts[$currentNamePartIndex];
    if(count($nameParts) > 2 && in_array($nameParts[0], $titles)){
        $foundTitle = true;
        $currentNamePartIndex = 2;
        $firstName = $nameParts[1];
    }else if(count($nameParts) > 2 &&
strlen($nameParts[$currentNamePartIndex]) == 1){
        $currentNamePartIndex = 0;
        $firstName = '';
        while(strlen($nameParts[$currentNamePartIndex]) == 1){
            $firstName .= $nameParts[$currentNamePartIndex].' ';
            $currentNamePartIndex++;
        }
        $currentNamePartIndex-1;
    }else{
        $currentNamePartIndex = $currentNamePartIndex+1;
    }
    $lastName = implode(' ',array_slice($nameParts,$currentNamePartIndex));
    /* odds and sods */
    /* camel case like ColinMcSomething */
    if($lastName == '' && mb_strtoupper($firstName, 'utf-8') != $firstName){
        $nameParts = preg_split('/(?=[A-Z])/', $firstName, -1,
PREG_SPLIT_NO_EMPTY);
        if(count($nameParts) > 1){
            $firstName = $nameParts[0];
            $lastName = implode('', array_slice($nameParts,1));
        }
    }
    /* colin@twit.com */
    if($lastName == '' && strpos($firstName,'@') !== false){
        $nameParts = explode('@', $firstName);
        $firstName = $nameParts[0];
        $lastName = implode('', array_slice($nameParts,1));
    }
    /* colin no last name */
    if($lastName == ''){
        $lastName = 'Empty';
        if($debug){
            $count++;
        }
    }
    $parts = array($originalName, $firstName, $lastName);
    return array('firstname' => $parts[1], 'lastname' => $parts[2]);
}

This is on Magento 1.9.3.4 The query I used to build a list of names from your database to test your name splitting function is

SELECT DISTINCT(CONCAT('"',prefix_sales_flat_order_address.firstname,'",'))
FROM prefix_sales_flat_order_address
JOIN prefix_sales_flat_order
on (prefix_sales_flat_order.shipping_address_id = prefix_sales_flat_order_address.entity_id AND prefix_sales_flat_order_address.address_type = 'shipping')
or (prefix_sales_flat_order.billing_address_id = prefix_sales_flat_order_address.entity_id AND
prefix_sales_flat_order_address.address_type = 'billing')
WHERE
prefix_sales_flat_order.created_at > '2017-01-01 00:00:00'
AND lastname is null
AND prefix_sales_flat_order_address.address_type = 'shipping';

I'm getting about 1.5% with 'Empty' as lastname.