@Thomas,
I don't think we're really in disagreement.
Not only can conflict not be ruled out, it inevitably occurs from time to time in families--particularly between teens and parents.
I'm just not sure that Gracie should come out of the gate fighting. She's got to sit back a little to see what unfolds, and she's got to give Katie a chance to also settle in. The changes in that household have occurred fairly fast, and a new baby will change even more. They are all in unfamiliar territory, as a new blended family, and just absorbing the changes, and adjusting to them, makes more sense than a competitive attitude, and a lot more sense than a combative attitude, for Gracie right now.
Quote:The damage to her family life is done
I'm not sure her family has been damaged. It's been altered, it's been expanded, but that doesn't mean it's been damaged. Once the initial disruption wears off, Gracie might well find her family life enhanced and enriched.
Having an adult female in the house, as her father's partner, is something, I gather, that Gracie really hasn't experienced before, or not since her mother left. That alone can take some getting used to, and some normal feelings of rivalry might be inevitable, even though Gracie, very fortunately, likes Katie.
And some of Gracie's anger toward Katie might already reflect that. If they both focus on the goal of wanting to have a good relationship, they'll be better able to weather the understandable anxieties and resentments that may surface during this initial phase of adjustment. It takes time to adapt to change and having to accommodate new people in our lives. Gracie needs to give herself, and Katie, that time.
I really hope that Katie becomes a positive influence in Gracie's life, and helps to provide something new and meaningful for her. But I wouldn't expect that to happen overnight, and Gracie has to get used to the disruption and change first--and, as I said in a previous post, I think she should talk about what she is feeling and experiencing with both her father and Katie, I think open sharing will be more productive than acting bratty to let them know she's upset. She's got to allow them to be helpful to her, if they can do that.
I think mainly Gracie needs to give herself time to deal with the changes, and just take things one step at a time.