ManyManyThrough relation with duplicate foreign rows

Questions
1

I have some code similar to the following:

class Order extends DataObject
{
    private static $many_many = [
        'Items' => [
            'through' => OrderItem::class,
            'from'    => 'Order',
            'to'      => 'Item',
        ]
    ];
}
class Item extends DataObject
{
    private static $belongs_many_many = [
        'Orders' => Order::class,
    ];
}
class OrderItem extends DataObject
{
    private static $db = [
        'Price'    => 'Decimal(5,2)',
        'Quantity' => 'Int',
    ];

    private static $has_one = [
        'Order' => Order::class,
        'Item'  => Item::class,
    ];
}

I need to allow the same item to be included in the same order multiple times.

Is this even possible? I’m asking because I’m hitting many issues in the GridField support, e.g. GridFieldAddExistingAutocompleter removes an item from the searchable list once you added it to the order and GridFieldDeleteAction deletes all the OrderItem instances with the same item ID.

2

For the posterity, I solved by converting the ManyManyThroughList into a couple of HasManyList, e.g:

class Order extends DataObject
{
    private static $has_many = [
        'Items' => OrderItem::class,
    ];
}
class Item extends DataObject
{
    private static $has_many = [
        'Orders' => OrderItem::class,
    ];
}
class OrderItem extends DataObject
{
    private static $db = [
        'Price'    => 'Decimal(5,2)',
        'Quantity' => 'Int',
    ];

    private static $has_one = [
        'Order' => Order::class,
        'Item'  => Item::class,
    ];
}

Then, instead of using GridFieldAddExistingAutocompleter (that seems to not support same ID insertions) I implemented a new GridField component, GridFieldAddFromList, that supports it.