That would be better way to proove your honest approach than responding to comaplins on the forum.
The airline said they had to charge me for the extra suitcase according to the policies of my Go To Gate ticket, so I had to pay 82,800 Japanese yen around 721 usd!!!! Some countries and do not allow children under 18 to enter the country unless accompanied by a guardian.
Gotogate also only offer 1 free change with the Flex option and will probable charge a service fee thereafter.