When you ask about grad school… what are you asking?
If your older daughter attends grad school, she will not get money because her younger sibling attends college. She will file for FA as an independent. Depending on the school… and program… she may receive grants, merit, or loans…any combination… or …just loans.
If you are asking if your younger D will receive FA with a sibling in grad school… the answer is… maybe. There are a few schools that meet full need that count grad school as 2 in school ( not many).