I firmly support giving her mythology books--of as many cultures as you can find. This will introduce R to the gods, and open her up to the idea that ther are many paths to choose from (only because many pagan groups focus on the wiccan-esque, and if she's attending some circles/gatherings now, I feel fairly safe in assuming that they are not Recon or otherwise).

But stick with what you know. It's one thing to open the child to the idea that there are different pagan paths, but you cannot, and should not, be expected to teach her any of those. Plus, she's 8--still in need of guidance from her elders.

Take the Christian ethics that her Grandparents have taught her, and build upon them with more pagan ones. Honestly, the Christian ethos is not all bad, but she already has the opportunity to learn those. I was raised Christian, and find few differences in the ethos I follow now from that of when I was younger--don't kill, don't steal from others (be it material or energy or even stealing their feelings by being cruel), etc. Add in reverence and worship of nature, the spiritual connectiveness of all things, the idea that you CAN question the things you are taught. Hopefully, the Chistian influence that she is receiving is moderate enough to cause as little confusion as possible.

You said that she likes animals--give her mini projects of learning about various animals, then discuss with her what that animal could teach her. For example, snakes. The Snake can teach a person about not being afraid of change, that growth is inevitable, but that, despite the pain (skin shedding is extremely uncomfortable and snakes are usually irritable during that time), it's worth the discomfort. Things like that. You use a totem book to lead the discussions after she has done her readings.