That’s true, she could’ve explained things to Alicia but I doubt she would’ve listened cuz she even said so herself, she doesn’t want to go back to their old life.
I mean she's not the most communicative person in the room on top of having a distant, rude, and incredibly stubborn brat of a sister who would sooner argue than listen what's MC trying to say, she also has a huge insecurity too. So I feel like she might've planned to walk her through everything after they both get out first so the situation could settle a lil bit for Alicia to swallow the information better later on, idk the novel probably has more of this
I don't like the fact that the MC cared enough to try to run away with her sister but never actually explained the real reason. She knows full well that the name Paula is the source of the danger. she isn't using a fake name for no reason. Even before the maid was murdered, she already knew that name could get her killed, not to mention now her sister yet still hasn't actually communicated that but still wants to run away with her.
What makes it more frustrating is that she never tells her sister she witnessed a murder or that the killer only knew her by the name Paula at the time. Like why not tell your sister that your name is linked to a murder as a sole witness. It feels weird for the MC to care so much yet leave out the most important information.
Even if her sister still chose to stay, at least it would be her own fault because she knew the actual risk. Instead she's making a decision without knowing the full truth. They probably had at least ten minutes walking to that marked tree so yeah it's hard to understand why Paula couldn't explain any of this.
It feels more like a writing flaw or a purposeful plot decision than a character decision. If the sister ends up dying, Paula is definitely going to blame herself for not telling her everything, and that's not something I want to see. Especially because it could be prevented but who knows what's to come.