I would say that you can pay her fees as well, have her come in on L-2, submit her AOS application with yours, and do AOS for all of you at the same time. That would be expensive, of course.
You will have to have your AOS approved first, and then she can apply for her immigrant visa. You should probably submit her DS-230 form with a copy of a barcode sheet to KCC, so that her interview could be scheduled at the embassy, if you don't want her to do AOS with you.