@utdragongirl
You do a really good job establishing the characters and their dynamics. You also make it crystal clear what the past event that's weighting in on everyone's heads-- though I would caution you to be careful as to not be too info-dump-y. There can be times where the exposition, whether it's in the dialogue or narration, seems a little necessary.
Also, as a story with a mystery flair, perhaps you could look into occasionally withholding stated information and instead, drawing your reader into making that conclusion themselves. If I may, somewhere where I'd insert something like that is in regards to the angel statue and the memorial plate. You build up a tense atmosphere, you call it Lizzy's memorial plate, and you have Alison whisper solemnly, which all cue reader to recognizing that Lizzy is either missing or dead.
The following line, then, that 'it had been six months since Lizzy went missing' feels almost redundant.
This is something that I would be on the lookout for. You do a good job of leading your readers to a conclusion, only to state it outright, which makes the exchange feel somewhat redundant.
You've got the trappings of a good mystery here, though! I know that sounded kind of harsh, but I enjoyed what I read of your story!
EDIT: Oh yeah, I forgot to plug my own story. Simulacrum is an urban fantasy/mystery story about cyberbullying, technowizardry, and the Power of Friendship! General audiences.