Fill Drop-down menu of Contact Form 7 with PHP

I want to populate the drop-down menu items of the CF7 from another database. The reason for this is that there might be a large number of items that might dynamically change every week. Adjusting the CF7 manually would be very frustrating.

I have tested the PHP with XYZ PHP Code plugin and it works. The code looks like this

$mydb = new wpdb('User','Password','mytable','localhost');
$rows = $mydb->get_results("SELECT `brand_name` FROM `brands`");
foreach ($rows as $obj) :
   echo ""$obj->brand_name" ";

The result of the script is values in double quotes, as requested by CF7 (Select):

"Taylor" "Line 6" "Kurzweil" "Nord"

Unfortunately, I cannot nest the short code of XYZ PHP Code into another short code of CF7.
This obviously cannot work: (select menu-446 (xyz-ips snippet="brands"))

Is there a way to do this?