Question: I have an older sister, Mary, and a younger, Tracy, who simply do not get along. Mary hasn't done anything specific like bullying, but I've never seen her openly accept Tracy or be nice to her. Tracy has tried really hard to gain Mary's acceptance, without success. Tracy can be impulsive and thoughtless; she might offend someone without realizing it. So to sum up 30-plus years of discord, they both have been mean and/or disrespectful to the other but neither recognizes it.
Now that we are adults with our separate lives, husbands, and kids, Mary has made it clear to my parents and to Tracy that she doesn't consider her a sister and doesn't want her involved in her life. As you can imagine, this is devastating to my parents, especially my mom, who blames herself.
Add to this, I am the "on call" sister for every person in this family. Mom calls me about what Tracy did to Mary and what Mary said to Tracy, while Mary will call me about Tracy and vice versa.
I'm asked by my mom what to do about this, and my answer is, we cannot do anything, they are adults and this is the situation they have put us in. Am I right to think that, or am I giving up too easily?
Answer: "I've never seen her openly accept Tracy or be nice to her," for 30-plus years? Sure sounds like bullying to me. Her own home was not safe for Tracy. Wow.
So while I agree that Mary is an adult and it's not in your power to make her do anything, this is not just "the situation they have put us in." In every situation that involves you, you make choices. In every situation where you make choices, you can make different ones.
That you have all parties calling you as their personal, sympathetic ear means you make choices in every conversation. Since every choice is an opportunity to change the outcome, yes, you are vastly underestimating what you can do.
For example, when Tracy calls you to complain about Mary, you can say, "Mary has been mean to you since before you can remember. Do you think any of us besides Mary can change that?"
Or when Mom calls: "I've stopped trying to fix or moderate anything. I'll give my opinion when asked, but that's it."
Or when Mary calls you to complain about Tracy: "If you're looking for ways to get along with Tracy, I'm all yours. If you're here to complain about her, then you called the wrong person." Or just, finally: "In 30-plus years, Mary, I've never seen you be kind to Tracy. If she's not your sister, then I'm not, either."
You've gotten a lot from being in the middle - a sense of importance, purpose, "middle child" identity. But it's not working. It's just enabling Mary's cruelty, Tracy's neediness, and your mom's unwillingness to accept and let go. So when you start making different choices in all these different conversations, keep yourself out of the middle by scratching off all the old goals of mediation and problem-solving. Replace them with these two goals for everything you say: (1) Tell the truth; (2) Keep responsibilities where they belong.