What happens to an approved PM when a "One Business Group" is created with a "Single Group CAMO"?

EASA Response:

If the Authority responsible for the approval of the aircraft maintenance programme remains the same, i.e. the authority of the State of registry of the aircraft, the CAMO may continue to use the programme, unless the programme needs to be modified due to changing operating environments, operation, utilisation, etc.

If the Authority responsible for the approval of the maintenance programme becomes the Authority of another member state, because an agreement is established between Authorities to do so, then it is necessary for the new Authority responsible for the approval of the programme to re-approve the maintenance programme for administrative and legal reasons.