Yes. I'm a supplementary card holder and I'm the only one who spends while my sister (principal) doesn't spend on her card at all.
However, every month, principal card needs to redeem the cash back and it will be automatically credited to principal card, if you want the cash back to be transferred to supplementary card then have to call CS to transfer.

if i applied the card a month ago,  but they didnt send me any rejection sms or any acceptance information. Should I call them and ask?

my wife and I also applied the cc for the air fryer from ringgitplus.

form already email last 2 weeks.maybe i need to call to ask the status else will be same as you, 2 months still no news. haha

Apply at where get the rm500 voucher

wanna ask anyone if have experienced using the JustOne platinum card to buy GSC tickets (rm7 per ticket) and you can feel that the transaction is "kinda purposely" being denied?
i have experienced multiple times whereby I'm already on the page where it says RM15 for 2 tickets but either SC won't send the OTP or once u click Confirm, it will go to Unsuccessful page. It's not the popup which tells you that the promo is fully redeemed.

For example, just now I tried to buy tix 3 times and I could see the page where it says RM15, but once I click confirm, it led to the Unsuccessful page. On the 4th attempt, then it said fully redeemed.