You can help a great deal by being a dependable older brother. You don’t have to take responsibility for replacing your father or keeping everyone emotionally together. You’re dealing with his departure too.

What you describe may be your sisters struggling with the upheaval. Anger and changes in behavior can follow a parent’s departure; that doesn’t establish that they’re deliberately manipulating anyone. The American Academy of Pediatrics describes these reactions in its [guidance on parental separation](https://www.healthychildren.org/english/healthy-living/emotional-wellness/building-resilience/pages/how-to-support-children-after-parents-separate-or-divorce.aspx).

A useful shift is to focus on your relationship with each sister and on specific behavior:

- **Stop trying to get the older sister to admit she’s angry.** You can address shouting even if you disagree about her feelings: “I want to hear what you’re saying. I’m getting overwhelmed, so I’m taking a break. We can talk again in twenty minutes.” Follow through and come back.
- **Ask about your part when things are calm.** “When you said I was the problem, what did I do that upset you?” Listen for a concrete example. If you interrupted, lectured, or spoke condescendingly, acknowledge it and change that behavior. You can take her feedback seriously while setting limits on insults.
- **Give the younger sister simple support and limits.** During a tantrum, keep your words brief: “I’m here. I won’t let you hit me. We can talk when you’re ready.” Once she settles, help her put the problem into words and ask for what she needs. Adjust this to her age.
- **Retire “be mature” and “you’re manipulating people.”** Those statements judge her character and intentions. Name the action and its effect: “When you shout over me, I can’t follow what you’re asking.” Make a clear request: “Tell me one thing you need.”
- **Spend time together that involves no correction.** Cook, take a walk, watch something, or help with homework. Ask how they’re doing and leave room for an answer. Listening and maintaining familiar routines are central recommendations in the [Child Mind Institute’s guidance](https://childmind.org/article/supporting-kids-during-a-divorce/).

With your mother, discuss a manageable division of responsibilities privately: “I can handle dinner and school pickups. I need you to decide the household rules and consequences.” Agree on what authority you have when caring for a younger sibling. With an adult sister, focus on shared household agreements and your own boundaries.

If your mother is too overwhelmed to manage basic care, help bring in another trusted adult or professional support. A relative, school counselor, or family therapist can share the load. If the conflict keeps worsening or disrupts school, sleep, or everyday functioning, that is a good reason to seek help.

For now, aim for something achievable: fewer lectures, calmer boundaries, and regular time together. Their immediate reactions won’t tell you everything about whether your support is helping. Keep room for your own grief and a life outside the household, too.