The way there it will be her nap time and on our way back it will be her bedtime but she's very observant so I'm afraid she's just going to want to look at everything and not sleep. And the seats next to me will be my brother and parents so I'm not too worried about her trying to hop on someone's lap

If you can schedule your flight around their nap time especially if you don't plan on buying them their own seat. There's not much arm room to move around much.

Yeah I just bought a back pack bc I figured that would be easier. Thank you so much!

Snacks!! New toys keep them occupied. I had a whole schedule for my son before we flew to his my husbands family in may. I bought a diaper bag backpack. Put diapers, wipes and a change of clothes. Snacks and pre made bottles in another part.