Nursing boundaries for a 16 month old with a new sibling

[txcyclamen]

I have a 16 month old DD and a 2 week old DS... Tandem nursing was never something I saw myself doing but when I got pregnant so soon I knew there was no way I was going to wean my DD. Two weeks in, I am really struggling with tandem nursing... I've read all of the threads and a bunch of articles that my sister sent to me. The problem is, nothing explains HOW to communication boundaries with a 16 month old. When she wants to nurse (which is ALL the time now) no matter how gently I try to say no or distract her, she screams and cries. It breaks my heart because she is such a calm, happy, independent child. I do not want her new sibling to create bad feelings, problems, etc for her. When I was pregnant, she was much more receptive to my needs and did not get upset when I asked her to wait or distracted her from nursing. Somehow the combination of the new milk and the new baby have made it impossible to turn her away without tears. She used to be very open to my "count down" and would usually pull off before I got to one... Now when I start counting she grabs ahoold of my shirt and starts crying. How did you create nursing boundaries for a 16 month old? The hardest time is at night when I am trying to sleep... everytime the baby wakes up to nurse she also wakes up and wants to nurse. I can sleep through one baby nursing, but not two.... any ideas?