C.D.
J.,
It's difficult to communicate effectively about this issue with the toddler who, after all, is still a baby herself. Sounds like when she gets up, she thinks 'up' is 'up,' and everyone should be there! My son was like that when he was little, and now his six-year-old daughter is like that, too ... and always has been!
Does she wake up hungry/thirsty? Does she have favorite toys that she can play quietly with? Here are a couple of suggestions:
On your way to bed, place a snack size baggie of dry cherrios in her bed, along with a sipppy cup of diluted juice.
Put some books in the bed with her, along with a favorite snuggly toy.
Continue with the side down on her crib so that she can come to you.
Another angle on this same approach is to make a game along with the six year old of being "quiet as a mouse." Go through the house on tiptoes, whisper softly to each other. Practice sending the girls for things, and tell them, "Now remember, be quiet as a mouse!"
Then ...
Tell the 19 m.o. when you put her to bed the night before that when she wakes up, she can come to your room for a breakfast snack and some juice, but that she must be "quiet as a mouse." She will most likely continue the 'new game' with you, and high praise is due when she makes it to your rooom without waking her big sister.
Hope this helps.