hi mate
i would suggest that some jump training would be a good option in-season for them. the obvious reasons being power and speed development, but also to help prevent ACL injuries (which females are about 70% more prone to than males).
try some standard box jumps, and some depth jumps with an isometric hold (check out thibedau’s book).
as for flexibility, females tend to have pretty decent flexibility as it is and they might be better served completing a dynamic mobility set as opposed to static stretching. cressey’s magnificent mobility dvd will cover everything you need in this regard.
just my humble opinion, hope some it helps!
cheers