Just ranting I really need to vent

So my fiancee works 11 to 12 hrs a day and my step daughter has recently decided she is going to sleep for 2 hrs then be up for 4 hrs before going to sleep the first night she did it she went to sleep at 930 woke up at like 1130 and then was awake til 530 am I'm glad it was the weekend so it didnt affect his work sleeping schedule but she has been doing it since we thought maybe it was because she had chocolate milk late in the day so the next few days we took away her sweet stuff after a certain time that did not work so she has been keep all of us (we have a 2.5 month old baby) awake and we dont get the right sleep neither does she tonight my fiancee got home at 6 had dinner with us and was asleep by 630 its 1215 and he still has only woke up to say a few words and back asleep we didnt even get to spend time with him because he was so tired he went to sleep what can I do to get her to sleep the right way also she is 2 also how do we get her to realize she isnt the center of the world I've been in her life since she was 4 months old so I'm not new to her by no means but as soon as my fiancee gets home everything has to be all about her even on the weekends he cant even pick up our son without her trying to shove her way in between them she has moments where I camt even sit next to him without her trying to shove her way in between us like I understand she is only 2 but she is damn smart plz send me any and all advice