It's a year away. Do you really have to ask right *now*? I wouldn't be concerned so much with the other girl thinking she's a replacement as the way filling this hole in your bridal party seems to be more of a concern than your friend having just died.
If and when you do ask, you can say something to the effect of having realized that time is precious and that you really want to share this experience with her. Assuming that's true, that is. If you're just trying to keep the sides in your pictures even, then skip it.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.