Pregnancy tradition for wife?

I am from a small rural village where it is common for only men to wear shoes and for women to always go barefoot when they are married. Marriage is therefore symbolised by a woman being always barefoot and wearing a silver anklet to show their marrital status. When pregnant, they will show this by wearing another anklet above the wedding one but this is worn only during pregnancy. It is common for a mother to pass the anklet she wore during her pregnancy to her daughters to wear whilst pregnant. My wife gave up shoes after our wedding to follow the tradition and has now fallen pregnant. My mother has given her the anklet she wore during her pregnancies to wear. However, my sister has fallen pregnant at the same time and is extremely upset that my wife has been given the anklet to wear and not her as she is a full daughter rather than a daughter in law. What is the best way to resolve this? My wife is so happy to have been given the anklet to wear but I have never seen my sister so upset.

Pregnancy tradition for wife?
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