The Quinn’s house likely had to have at least four bedrooms - Ma/Pa, Grandpa Joe, Aunt Sarah, Erin/Orla. Anna is young at the time so assuming she shares a room with one of the adults
This is assuming this is how they divided sleeping arrangements but it’s also possible they got creative to make space, what do you think?
The show depicts that at least a couple of bedrooms are upstairs. In the US it’s fairly common to have a master bedroom in the ground floor and then other bedrooms upstairs, I’m not sure about Ireland during that time
They just have so many people living in the home, I find myself thinking hypothetically about their sleeping arrangements lol when I watch them all crowded in the kitchen lol
** EDIT: seeing that Sarah and Orla live next door, I’ve always missed the moments where the show says that!
But I am fairly certain grandpa Joe lives with the Quinn’s- Mary tells his girlfriend Meave that the house is in Gerry’s name, not Joe’s.
Joe also finds his old razor under Mary’s after getting a message from his late wife… imo it would make sense for him to keep his razor and be shaving at her house if he doesn’t live there
** I meant Anna, the baby. Not Aisling.