It's a very unfortunate turn of events at a tragic time in your lives. Firstly, my deepest condolences on your loss, I wish you and your family a long life. At such a hard time, it's not inconceivable that your emotions surrounding the loss of someone so dear to you has become mixed up with the anger at your sister's mistake. I don't know you, nor you me, but I'll offer some advice in earnest all the same.
Your sister made a mistake, but now isn't the time to blame her or let your (justified) anger get the better of you. Your thoughts should be on your father and on your loss. You should be grieving and supporting each other right now, and when you have a little time and distance, that would be the time to speak to sister about her mistake at such a difficult time. For all you know it could have been hopeless naivete or genuine good intentions. The difference will be in whether she made an honest, well-intentioned mistake about which she's remorseful or a knowing act of subterfuge and theft. Decide when your head is clearer and after you've mourned, don't let it overshadow your loss.
My sincerest sympathies again.
Your sister made a mistake, but now isn't the time to blame her or let your (justified) anger get the better of you. Your thoughts should be on your father and on your loss. You should be grieving and supporting each other right now, and when you have a little time and distance, that would be the time to speak to sister about her mistake at such a difficult time. For all you know it could have been hopeless naivete or genuine good intentions. The difference will be in whether she made an honest, well-intentioned mistake about which she's remorseful or a knowing act of subterfuge and theft. Decide when your head is clearer and after you've mourned, don't let it overshadow your loss.
My sincerest sympathies again.