Step daughter watching baby tomorrow

Ga

So my step daughter goes to the same school I teach at and tomorrow is a half day and I have to stay and work on stuff all afternoon 😒. Would it be ok letting her watch her? The baby sitter would just have to watch her from 7:00- till when ever she gets home which should be around 1:00. I know they say you shouldn’t have the older siblings watch the younger ones but I’ll be home around me 3:00 anyways. TIA!