Holders of the underlying ordinary shares may request to convert these shares into an ADR. Similarly, holders of an ADR may request to convert to the underlying ordinary shares.
IB will offer this conversion for the shares listed
here.
...
In the event the security is not listed within the table, customers may submit an Inquiry Ticket. Within the ticket, please indicate the security you wish to convert and the number of shares. Upon receipt, IBKR will review the request and provide information on whether the action will be made available.