Do i need to add the newer SIM to my own existing account to do this?

Hi everyone, 

I've been with ID a few years. I've got an active SIM and one account for my number.

I got a second SIM for my grandfather, which is actively used in his phone now. 

I don't think I've ever registered his number with an email address (in ID Mobile app nor here). I ordered his SIM using my name, address and email initially.

As we need his SIM to be associated with his email account, and with his bank card now, what should I try to do? 

Thanks for any help, have a good day! 

Jules