Add I cloud account

Hi there

I tried to change the method of payment as my brother in law's card has registered to this account. The problem is that the account is Korean account and i am having New Zealand card as i am living in NZ. So i cannot register NZ card to the Korean account to purchase Icloud storage. If i buy Icloud storage as NZ Apple account, is is possible to merge the Icloud Korea account?

Thanks

Ava