I feel like you'd have to make it understood in the book why the first-person character knows what's going on. Usually when you're in first person, you're looking for an intimate POV. She's telling the story that happened to her from her perspective, and she didn't know back then what was going on beyond her experiences unless she had someone tell her them, and even then, she wouldn't know they were going on at the time they were going on.
If it's a frame story, where the narrator acknowledges that it's a story to some sort of audience and right up front makes it clear that she knows more in the present time than she would have at the time, it makes it easier to accept that the character is telling a story and might even be guessing that other person's part for the sake of the story.
Or you might have to say, every time, something like, "Now, Jenny told me later that right at this moment, she was..."
But honestly, without some convention for explaining why the 1st-person narrator knows (or thinks she knows) what's going on beyond what she's personally experienced, I wouldn't accept her knowing it. Even in past tense, we're right there with the narrator in the moment she was experiencing. It's jarring to suddenly jump to knowledge that she can't possibly have in that moment.