If she's already gone with a publisher (which she has), it's no longer up to her - she (likely, but it depends on her contract) can't submit that work to a sepa

If she's already gone with a publisher (which she has), it's no longer up to her - she (likely, but it depends on her contract) can't submit that work to a separate publisher even if she wanted. I'm also not sure I buy the people saying that she should go at it alone next time, and solely self-publish. Doing so means that, among other things, she'd have no advance to live on while writing it, no editors to work with her on making the copy better, no typesetters to make the text flow well on whatever platforms it gets distributed on, no artists for cover design, no translation support to release international editions, and - this is the important one - no advertising and distribution support to get the book places into bricks-and-mortar stores (as most stores look down hard on self-published books). It's not just a matter of saying "OK, I'll self-publish"; there are all sorts of other costs that are a part of publishing a book that a publisher normally covers, which you have to pay for yourself should you self-publish.