Form AP1 - panel 9

The sole owner of the property died, whose details get supplied here? (The address for service).
The person making the application, or the owner to be?

C B - form AP1 is a generic form for updating the register. Panel 9 is used to provide the contact address(es) for the registered owner(s) as appropriate
Guidance: completing form AP1 - GOV.UK

So in my instance, the dead owner?

C B - it may help to explain what your 'instance' is and what it is you are trying to update the register for?

Transfer of ownership to the beneficiary stated in the will. I have grant of probate but I’m not the beneficiary.

C B - many thanks. So you are applying to update the register following the death of a sole legal owner. And using forms AP1 (application form) plus AS1 (Assent - transfer) and forms ID1/ID3 as appropriate
So form AP1 will refer to the applicant (panel 6) as the new legal owner (beneficiary) and panel 9 will confirm the address(es) that person requires
It's important to look at form AP1 as being the one that ties all the others together into a single application 

Thank you for the clarification.