silly me, i didn’t even welcome you properly!
WELCOME!
yes, the timothy pellets are definitely good. i wouldn’t switch those at all. just the alfalfa hay. or like Sarita said, offer both for some variety.
i’m guesing the woman meant well, but being sisters has nothing to do with whether they can be in the same cage. any two buns can be housed together when they are very young, but once they reach sexual maturity, they will need to be split up until altered. it’s rare for two buns, esp. two unspayed female buns to be able to be housed together with aggression. females are actually more territorial than males.
i would make a vet appt as soon as possible to have them both sexed by a professional (by “professional” i mean a vet). if they are in fact both female, they will probably be okay caged together for another couple months, but then you will need alternative housing until after the surgeries.
have you done research on altering rabbits yet?