Welcome to the forums!
I'm very sorry for the situation you are currently in.
You should take advantage of the quarantine time to keep on training Luna and to pay close attention to your rescued girls' behaviour in order to see if they truly get along well and are closely bonded to each other or not.
If by chance you notice that Pearl is also aggressive towards Alice, then you would know that housing Pearl alone on a separate cage would be the best option to ensure your other budgies' safety and welfare.
Depending on personality, housing two females in the same cage may not work, and housing an odd number of budgies who all happen to be females also raises the chances of fightings/disharmony in the flock.
With time, you will be in a better position to make the necessary arrangements which will benefit all of your budgies in the long run.
For now, you can continue to closely watch their behaviours and interactions.
Best of luck with everything!