Aer Lingus has committed to running six former Stobart Air routes previously operated as Aer Lingus Regional until the end of August.
The Irish carrier stepped in after Stobart Air ceased operations late on June 11.
Aer Lingus is progressing plans for services beyond August, details of which will be announced shortly.
BA CityFlyer has announced that it will operate four routes for the rest of the summer.
But travel on other routes from Dublin to Kerry and Donegal; and Belfast to East Midlands and Cardiff until at least June 27 are cancelled.
Aer Lingus is ready to operate the Dublin-Kerry route, subject to an appropriate public service support arrangement being put in place.
The carrier is also “actively exploring” options that would enable the provision of a Dublin-Donegal service.
Customers scheduled to travel on the Belfast City-East Midlands route before June 27 are being offered alternative flights.
The airline said: “Aer Lingus is transferring customers on to replacement flights in order to minimise disruption. Where no replacement flight has been scheduled, Aer Lingus is booking customers onto alternative flights.
“Aer Lingus wishes to apologise to Aer Lingus Regional customers who have been affected by Stobart Air ceasing operations.”