A.A.
Hello E., I clearly understand! My daughter just had a baby and he started off sleeping through the night, then when my daughter got sick, then he started waking up and wanting to stay up different times throughout the night. But, to get him back on track, because we started losing sleep because of him crying and wanting to play. What I suggested to her, and now to you, and what I did with her brother when he was doing the same thing years ago, lock down the time or times that she is waking up through the night, set a time that will work that will allow you and her to get some sensible sleep,then with that, at the next feeding that is at that night time feeding, give her a nice warm bath, feed her, then lay her down. maybe even set a radio with some soft ocean music, something that is soothing. You need to stay in control of the timing and set the pace, along with helping her get on a set schedule.
Good luck, A.