Not selfish at all.
Just be careful, since she's new to poly, of her feelings and expectations. Make sure to communicate often and clearly. Maybe encourage her to do some reading on poly if she never has before (www.morethantwo.com
is my go-to).
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.