Find a used 14" bike that she can use (and hopefully your son will be able to at some point also). It will help her feel comfortable and safe while riding.

I'd back off on trying to teach her to ride on two wheels. She will learn on her own, i.e. don't force her to do it. Keep riding yourselves. Hopefully her friends or other kids in the neighborhood are riding. Peer pressure works best to encourage learning the skill.

My first learned to ride at 5, second at 7, third is almost there at 4. The 7 year old surprised me when they started riding. I really wanted it to happen last year but I could see behavior very similar to your daughters. Those foot bikes can be good, it was playing the game of how far can you go without touching that got the 7 year old to find balance.

Good Luck.