Would this mean that the girls co-write a book, or that they write a book each or are both possible interpretations?
Both interpretations are possible, but we would probably add something to make it more explicit:
- les filles écrivent chacune un livre
- chacune des filles écrit un livre
- les filles écrivent un livre ensemble
- les filles co-écrivent un livre
Thanks a lot! Have a lingot for being such a great help for us french-learners! You are awesome! :D
As far as I know fille also means daughter. I used this version (two daughters are writing a book) but it was not accepted.