My daughter is the exact same age. Any change in routine throws my daughter off SO BAD. Her birth Mom has a different bed time routine, I am sure. If she ONCE let her out of bed, that is all it takes for her to learn she CAN get out of bed. I have a wonderful pediatrician who says that a bad habit starts the first time you allow that behavior. (whatever that behavior might be) She went on to say that for as many times as the behavior happens, know it will take about a week of strict consistancy on your part as the parent to break it. So, if her birth mother let her out of bed for three nights,,know you have three weeks or so of strict consistnacy to break it. Is she already in a big girl bed?
19 months is a very interesting time for the whole family. It is the time to really start setting rules and sticking to them to teach dicipline...that Mommy and Daddy are the boss and she has to learn to respect that. She is not too young, by any means, to learn that. It will be even harder for you, as you have to get three parental figures all on the same page for the consistancy aspect of her learning and dicipline. With alot of talking among the three of you..honest and open communication...I am sure you can get on the same page. I will be thinking of you all,,as this seems like a diffacult situation for any parent to be in. I am sorry to hear of your stillborn. My heart breaks at the thought. I had a miscarriage, (which I know is not the same thing,,but still a loss) You and your family are in my prayers and thoughts.
She can be all of the things you said, well loved and diciplined, but it is the consistancy that is key with any child.
Many good wishes and Blessings.