https://www.epo.org/en/node/specifics-oral-proceedings-9

Am I allowed to share the connection details provided by the EPO with my client or any third party?

If your client wishes to attend the oral proceedings as an accompanying person, you may share the connection details with them. Note that the opposition division must be informed in advance of the attendance of your client as an accompanying person. See Guidelines E-III, 8.5, for information on requests for submissions by an accompanying person.

A request to attend oral proceedings as a member of the public must be filed by or on behalf of the person concerned. The connection details provided by the EPO for attending oral proceedings as a member of the public are intended for the sole use of the requester and must not be shared with anyone not mentioned in the request. The requester accepts full responsibility for any consequences arising from the unauthorised sharing of the connection details.

Further information about access to oral proceedings by videoconference before opposition divisions