Anonymous wrote:I call my sorority sisters “sister”. It means nothing.
She will likely call her MIL/FIL”mom” and “dad” too. I think it’s great. So many people hate their in laws. She know them for 3 years and loves them. They are off to a great start.
Anonymous wrote:OP I think your emotional reaction is totally understandable. Your sister is one of your best friends and you cherish that relationship. You are worried that her relationships with her soon to be SILs will diminish your relationship with her. That's not an unreasonable fear; she will probably spend more of her holidays and free time with her husband's family than she does now, and it may take more work to sustain your relationship.
I don't think it's really about her calling them "sisters," that is more just the symbol of what you are worried about.
If I were you I would talk to your sister about this. I wouldn't do it in an accusatory way and would not bring up the "calling them sisters" thing, but would say that you are so happy for her but you cherish her as your sister very much and have some fear that you two will become less close as she becomes more part of her husband's family. You could say you hope you continue talking on the phone every week or seeing each other every summer or whatever it is you do now to remain close.
This way you're not saying anything negative about her new family members, but just telling her how important she is to you and that you want to be conscious to maintain that.