Using existing VAT number while waiting for Group VAT number

My company has recently applied for a Group VAT number to include its new subsidiary company. I wanted to know how we would apply for a special dispensation with HMRC to continue using the existing VAT number till we get our new Group VAT number? What are steps we would need to be able to issue invoices till we get the Group VAT number and what would we need to do regarding re-issue of those invoices with the new VAT number? Thanks in advance.

Hi,
You can not continue to use your single company VAT number after the date the company joins a new VAT group as the single company VAT registration will be deregistered at this point.
If you need to raise invoices after the date the company forms a VAT group but before the VAT group number is issued then please see the guidance below:
Keeping records and charging VAT — when to start
Thank you.