This script will work on simple implementation into your gamescript. Script was tested with ~40 players online at once.
Just include the script into your gamemode and make sure to trigger the server-sided events to let a person carry another person. Please implement a check if a person is already carrying another person. (which can easily be done by checking "carry" shared variable.
Report bugs? Mention me on RAGE:MP Discord or with DevGrab#0815