New GC

Common courtesy would be to thank all posters for their thoughts and to say they will be read when OP has time.

You don't even know if she has internet at home or can only log in from the public library, or if she's fallen ill since posting. I wish people would not be so ready to give each other a hard time.

Ask yourself this: 'Would my daughter and her family do the same for me if I needed occasional care?'.
If the answer is no then there's your reply to your daughter.
It works both ways.
Why ask us about a life changing move you've been asked to make.
We don't know how deeply rooted you are in your present community.
We don't know what moving costs you would incur.
We don't know the price your oresent house would command or indeed the price of houses near your daughter
If it seems like trying to uproot an oak tree, it would probably be as traumatic.
Personally, I would laugh at such a request, were any of my AC foolish enough to voice such selfishness.

Ponymoore couldn't you go and stay for a while when the baby arrives if she needs the help (you don't say if she's got a partner/DH/SO). To up sticks like that is a decision that shouldn't be made just because you're asked and as others have said, you have your DGDs to think of too

You will jeopardise your relationship with your twin gd so no, don't do it. Its unreasonable of her to expect you to make such a move. I would take the option of staying with her regularly if you can manage that. Or tell her to move nearer you so your gd can build a relationship with their new cousin.. Cousins are our first friends and often have the most special bond. Good luck

Thankyou for all your comments, they are most appreciated. Sorry for the delay in replying but have been away for a few weeks.

Ponymoore, congratulations on your coming gc! Such joy for dd and the whole family! But I agree with the others, don't abandon the gds who already count on you or move away from friends, doctors, etc. that you know and trust. If dd feels the need for your help, let her move closer to you. She may feel you "did it" for her older sib and now it's "her turn," but she needs to understand that it doesn't work like that with gc's feelings.