Mom with dementia thinks she had a baby. She was waking me up to look for the baby at night. My sister got her a doll that she thinks is her baby. She questions a few things about the baby. I am worried and not sure how to handle the situation if she starts questioning if the baby is real.
You are now to the point with your mom that you must meet her in her world, not visa versa. If she says it's real, then it's real. If she says it's a doll, then it's a doll. You will find that it's much easier to just go along with whatever she says, even if that changes daily. Best wishes.
That doll IS a real baby to your mother, so it's a real baby to you. Take your mother's lead when discussing the baby, and if she thinks something isn't quite right (which I doubt she will), tell her it seems OK to you, or "what you think might be wrong?" Let her set the narrative, and you may have some great conversations with her.
One thing that did give her comfort while in MC was holding on to a life sized doll. A life sized animated dog was also a hit in the unit.