Dear Madisgram
You need to hold your sister responsible for her actions. If this would have been anyone else would you not press charges? I know you love your sister, but she is a thief.
Please don't allow yourself to be responsible for her actions. In other words. You did nothing wrong and even tried to protect your sister. It is her way of saying "I have no intention of paying you back". Remember, Wills can be changed as fast as they are made. Make a copy to show you and once you've seen it she calls and has it changed.
By not doing anything all these years, you have come across to her that you won't do anything about it so she has nothing to worry about.
I will pray for you
Diane