Hi all, these books were published in the 1980s, each had different girls names and they were always choosing 2 different guys and they always took place around major events in history.  So far I have found for her:

Marilee (Sunfire, No 9)
Author: Mary Francis Shura

Nora (Sunfire, No 26)
Author: Jeffie Ross Gordon

Diana (Sunfire, No 29)
Author: Mary Francis Shura

Jessica (Sunfire, No 6)
Author: Mary Francis Shura

Laura (Sunfire, No 10)
Author: Vivian Schurfranz

Danielle (Sunfire, No 4)
Author: Vivian Schurfranz

I have a few more of the titles on my WL---willing to pay one credit each as long as the pages aren't falling out of the books we will take what we can get.  Please let me know if you can help me help my sister collect these.  Also if you know of a website that might have the complete list that would be great as well, as i'm just working through PBS inventory. :)

I remember these!  I don't think I have any anymore, but I read several of the series when I was younger.