Rosalind wasn't quite sure what to make of this new development. On one hand, she was thrilled her ultimate goal seemed to be getting closer. On the other, she was concerned this would mess things up so getting her siblings back would be impossible.
In her original timeline, her parents weren't supposed to get married this soon. What if this changed things? There was nothing she could do if it did!
She couldn't exactly say "hey, can you hold off getting married until 2023 and having kids until 2026?" though. That would be really weird and they wouldn't go along with it. At this point, all she could do was watch and wait the way she had all these years.
Rosalind hated it. She hated the uncertainty of hoping for something she wasn't even sure was possible. Her life here didn't even feel like it belonged to her. She was surviving rather than living because she was mentally stuck on the childhood that was stolen from her by the time machine.