The tone for the goodbye farewell letter to sister can be informal. It depends upon your relationship with your sibling. Once you have inquired about her health in the start, you can simply move to the topic of saying goodbye to her. Tell her the reason why you are writing this letter and where you are going to go. Moreover, explain to her that you are going to be writing her more letters in order to remain in touch. Goodbyes are not an easy thing to do, especially when it comes down to your own siblings. However, once you have taken the decision, defend it.
Sample of Goodbye Farewell Letter to Sister
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I hope this letter finds you in good health. I am writing this letter to you as a goodbye before I leave for my university which is in America.
I know it is hard for you to believe it, but I am actually leaving London to find greener pastures. This is because I could not get into a good university in England and America is giving me a better opportunity to grow. I realize how you feel regarding the fact that I kept all this from you, but you must understand that this is for my betterment and it will help me grow as a person and as a professional, something that you have always wanted from me.
Even though this letter signifies goodbye, it does not mean that we will not remain in touch. I would love to come back and see you again. I hope that you are going to write to me once I go and settle down and give you my address.
I love you, little sister, and I hope you understand that my decision was not because I want to move away from you but because I want to grow as a professional.
Lots of love,