Have you read the manual????
I cant see anywhere it says it need 63A.
Plus you can also take a little diversity into account.
Dont forget that this work will need an EIC for the new circuits and notified to your LABC.
Good luck.
Indeed, if the drop is one single concentric then there is more than likely PME available.
This could be checked at the CU by switching off, removing bonding and performing a Ze.