If the Fangs lose immunity again (which they probably will), they should get rid of Kelly, but they should do it by voting for Sugar. Here’s how it should work.
The four original Fangs (GC, Ken, Crystal, and Matty) vote for Sugar. Kelly also votes for Sugar. Ace and Sugar will vote for Kelly. Sugar plays the hidden immunity idol, the five votes against her do not count, and Kelly is removed from the game...and Sugar no longer has the idol.
If the original Fangs vote for Kelly, she’ll be removed from the game and the results will be exactly the same...except that Sugar will still have the idol.