What is Jane's main goal with Lassiter? What is she trying to get him to do? How is she using Fay to get what she wants from Lassiter? How is she using Lassiter's attraction to her to get what she wants?

Jane's main goal with Lassiter is to get him to stop killing Mormons. Jane thinks if he gives up his guns, he will give of his murdering ways, so she is using Fay to appeal to the soft side of Lassiter. In Jane's mind, if Lassiter can love Fay, then he may think twice before he kills a man and leaves a child fatherless. Jane is using her own beauty because she realizes that Lassiter is attracted to her and she thinks she can trick him into doing as she wants because he loves her.