Bisexuality Support Group
Bisexuality is a sexual orientation which refers to the aesthetic, romantic, and/or sexual attraction of individuals to other individuals of both their own and the opposite gender or sex. Most bisexuals are not equally attracted to men and women, and may even shift between states of finding either sex exclusively attractive over the course of time.
As for the thing I wish my family had done: Not immediately try to convince me that any form of homosexual contact was an absolute disgusting pile of evil at every turn. (This is mainly my father's personal reasoning) I wish they would have just helped me learn about being in a loving relationship regardless of my partner's groin-gear.
What I (In my horribly finite wisdom) would advise you not to do is be afraid to participate in the exploration with her. If she wants to explore being in an open relationship and being intimate with other females for the first time then I would very carefully nurture her curiosity. Ask her questions, answer her questions honestly but with tact and kindness, and show a genuine interest in her explorations. I hope you both find a multitude of happiness and peace with your newfound knowledge ^^