IRRE: Connecting data is only possible with new data
Having a record with IRRE-Options there is only an icon for new records.
It's unimpossible without direct access to database to connect existing records to the current one. Icon and function to connect existing records are required.
It should be configurable in TCA if the connected data have to be unique or if one record can be assigned to different parent records.
(issue imported from #M15647)