I emailed them the proof and they took 10 days to reply. They approved our ARC and send request for their passports today.If you have the money send it to them , and claim it later on for the sake of your application . If you don’t mind the time of the back and forth , send them an email about your flight back , to which they might ask for a proof that you purchased your ticket and thats not what you want really !
Good luck ! IRCC has been very disappointing recently