Swallows nest - changes to the shed

Swallows have nested in our Victorian shed for over 30 years -we leave the door open they nest in the high eves. We would like to put a ceiling in so we can use the shed while they nest the ceiling height would still leave a large attic. We aim to create access points in the brickwork  for them to enter the eves-and a loft access to clear out the droppings every year Do you think this will still be attractive for them to return as we would not want to do anything to stop the continuous occupation.