If you are registering your company as standalone, you can give any one of the UAE bank accounts. You have to provide the name of the bank, branch name, account name and IBAN code. You should give the bank account of the company for which you are registering, and not of any other related party bank account. If you are registering for VAT under TAX group option, you can give only one bank account number; not of all companies of the group. This bank account will be of the representative company which you choose while registering for VAT as Tax Group.