I think the point about the 'baby problem' was that this might be less a case of helping her get used to the baby and more a case of helping her learn to entertain herself and/or providing other entertainment. i.e. it might not be she needs to get used to the baby at all but does need help getting used to a different routine.
Ideally this would have been done way before the baby arrives. I realise that's not helpful for you now but might be for future readers of this post. The routine should be changed, slowly, months before baby arrives so the dog doesn't link the two and has time to settle into it before the stress of a baby arrives.
Anywho...
I would suggest going slowly. Whilst she cannot now have fuss all the time she wants, she will need time to get used to that fact. Which is going to be busy for you! Perhaps make effort to speak to her a lot, while you are seeing to the baby, give her eye contact etc. Over time you can slowly reduce how much you do this?
Things that she can entertain herself with would also be useful. Kongs, snuffle mats, lick mats, cardboard boxes to destroy, scatter feeding, etc. I think I'd be tempted to introduce them during baby feeding time (maybe behind a gate) so she gets the idea that baby feeding also equals lovely treats for her?
Did she always sleep downstairs or is that also new for her?