Yes that is a good point. We don't know how contact was made with her family earlier this month, but I do recall reading that Tanya didn't have her own phone.
IMO this "family contact" situation is strange. Did Tanya contact her family via phone, text, FB, or some other method? If it was via phone or text, who's phone was used? More importantly, did she say where she was or provide any details about her disappearance?
If the entire contact with her family was via text messages, and her voice wasn't heard, then it's at least possible that Tanya herself did not sent the messages.
I'm assuming Tanya is still technically 'missing' but this situation seems most unusual.