I've name changed as this could possibly be outing.
DS (20) has been in a relationship with a woman for about a year and half, she's slightly older and has a 5 year old from a previous relationship, they've been living with me for about a year as the child's dad found out where she was living, it's all been fine, they contribute a little financially and they do their fair share of cleaning and cooking. The only issue is holidays as the 5yo is sleeping in what was the spare room/ previously DS1s room and DS1 is at uni but when he comes home from uni, the 5 yo has to sleep in with DS and his mum which isn't ideal but they don't seem to mind.
They recently announced that the girlfriend is pregnant (about 10/11 weeks) which was a bit of a shock but they seem happy with the news, I've told them they have to find their own place to live before the baby arrives and DS has said I'm selfish as it's my grandchild, they won't be able to afford it as he's just started uni, they'll make the lack of space work and has tried blaming DS1 for coming home during holidays as he said if he didn't I wouldn't be asking them to move out.
It's probably my fault as he is my youngest so I probably have made the wrong decision to allow them all to stay etc as I didn't want him to move out yet, so feel free to judge but AIBU?