When I was 26 I’d been working as a doctor for a year so was arguably in a better position than DD1. If I’d have got pregnant, I still wouldn’t have been in a position to have a baby: I was living in a shared house; I had huge student loans (private student loan with a fixed monthly repayment as well as the usual student loan with the income-linked repayment); I wouldn’t have been able to afford childcare etc. Moving back in with my mum and making my poor decisions her responsibility wouldn’t have been fair on anyone, so you know what I would’ve done? Taken responsibility for my own actions and had an abortion.
OP, you’ve been avoiding any of the questions asking if DD1 and her boyfriend work. That makes me think that neither of them have jobs, pay rent etc.
How are they going to pay for a child?
Be honest with yourself- they aren’t. You are. When your grandchild is living with you and crying because he/she is hungry, and there’s no milk in the house, are you going to ignore them, or are you going to buy milk? After the first time, are you going to wait until it happens again, or are you going to keep stocking up just to be safe? Is DD1 going to bother providing for her child when she knows you will do it for her?
Think back to when you were pregnant with DD1. Where were you living? Who was paying your bills? What were you doing to prepare for your child’s arrival? How much did you have in savings to pay for baby furniture/clothes etc? Compare this to where DD1 is now.
You say you can’t tell someone what to do with their body. But when that someone is completely dependent on you from both a financial and practical perspective, you can absolutely make them see the consequences of their irresponsible choices. And yes, “choices” is the right word. Either DD1 CHOSE to try to get pregnant despite her current situation (in which case she hasn’t got the common sense to be able to raise a child) or she became pregnant “accidentally” (in which case she isn’t responsible enough to use contraception properly) and CHOSE to continue the pregnancy and have a baby. Either way, she needs to see the reality of the situation. She’s CHOSEN to have a baby but she doesn’t get to choose what to do with your money and your time/resources. She and her boyfriend need to explain exactly how they are going to care for and provide for the baby without using you as the answer to everything.
You say that you’re hoping the boyfriend will step up when the baby is born but I think that everyone here can see that DD1 also needs to step up.
As someone with AuDHD (although not diagnosed until my mid-30s - genuinely well done for advocating so well for DD2 that she was assessed and diagnosed as a child), the idea of a newborn and another adult moving into my home, my safe space, is horrific. I need my home to be my haven, where I can decompress and recharge after being drained by dealing with people at work etc.
I hope DD2 has asked her grandmother about the possibility of moving in with her. I suspect she has. I also suspect that it wasn’t a spur of the moment comment, but rather a back up plan that’s existed for quite some time, and has been thought through to the Nth degree.
Good luck. I think DD2 is the only one in this post who actually sees the reality of the situation (although maybe your DH does too? You haven’t said anything about what he thinks/wants). Listen to her. She sounds sensible.
If you let DD1 bring her boyfriend and raise their baby in your house you are, by default, choosing her over DD2. I know you want to support DD1, but support for a grown adult doesn’t mean taking responsibility for their poor choices. It means helping them to take responsibility for themselves.