BA has planned to hold the fort of its sister airlines within the coming few months of this year. Madrid Barajas had a pretty good number of flights running via route Spain-London which as a whole is handed over to the BA.

The Iberia and other carriers that flies through this route may be affected due to the sudden changes in the taking over of control.
British Airways Takes Over all Spain - London Flights of Iberia

The initial talk sounded as if only the Madrid Barajas will hand over its carriers in-charge to the British Airways, but the later part of description stated clearly that all of the flights that land London from the source as Spain will be affected due to this.

All the sister crafts of Iberia will be given in the hands of the BA which was later understood as said the Spanish press. Though all these confusions persist, the actual and finalized timetable of the flights have neither been released.